5 May 2003
MEDITERRANEAN ACTION PLAN
Meeting of the MED POL National Coordinators
Sangemini, Italy, 27 - 30 May 2003
STRATEGIC ACTION PROGRAMME
SEWAGE TREATMENT AND DISPOSAL
IN THE MEDITERRANEAN REGION
In cooperation with
Table of Contents
1. INTRODUCTION 1
Purpose of Document 1
Target Audience 2
2. ENVIRONMENTAL CONSIDERATIONS 3
Background water quality 3
Wastewater characteristics 3
Characteristics of wastewater discharges 5
Dissolved solids 7
Suspended solids 7
Other considerations 7
Environmental uses and water quality 8
Use area definition 8
Environmental Quality Objective and Environmental Quality Standards 9
Legislation and role of authorities 12
Role of authorities 13
3. MANAGEMENT FRAMEWORK 16
Aims and Objectives 16
Strategy and Principles 16
Control Mechanisms 17
Economic tools 18
Effluent Quality 19
Effluent management and environmental values/water uses 19
Technology-based guidelines 21
Determination of effluent quality 21
Receiving Water Body and Aquatic Ecosystem Protection 22
The Role of the Wastewater Company/Authority 23
Community Consultation 24
4. OPTIONS FOR EFFLUENT MANAGEMENT 26
Waste Minimisation 27
Managing the Collection Systems 28
Managing the Treatment Systems 30
Effluent Reuse 30
Land Application 32
Discharge to Coastal Waters 35
Discharge to Inland Waters 37
Treatment of wastewater 38
Treatment processes 38
Sludge processing and disposal/reuse 39
Selection of flow scheme 41
Submarine Outfall 42
Mixing zone 44
Treatment and disposal design philosophy 45
Environmental quality objectives 45
Use areas 46
Design of wastewater sanitation schemes/sewerage schemes 46
5. GUIDELINES FOR DISPOSAL 49
Guidelines for Land Application 49
Guidelines for Coastal Waters 50
Guidelines for Inland Waters 54
6. SAMPLING AND MONITORING 58
The Environment 58
The Effluent 59
Appendix 1: Glossary 62
Appendix 2: Bibliography 66
Mediterranean region generates large volumes of wastewater, with urban water use
alone accounting for about 38 x109 m3/year. Out of it, the northern region produces 23 x109
m3/year; eastern 7.5 x109 m3/year, and southern 7.5 x109 m3/year. Wastewater also comes
from industry, commerce and tourist resorts. The wastewater from urban areas,
“urban/municipal wastewater”, means domestic wastewater or the mixture of domestic
wastewater with industrial wastewater and/or run-off rain water. Treated wastewater, known
as effluent, is normally discharged to the environment (land, inland waters, and coastal
waters), requiring proper management to protect public health and the environment.
A wastewater collecting system:
- receives domestic, commercial and pre-treated industrial wastewaters;
a wastewater treatment and disposal system:
- treats the wastewater to the required level;
- discharges the resulting effluent and solids into the environment.
In providing this service, the wastewater sanitation system (the combined collection,
treatment and disposal system):
- manages the liquid waste produced by a community, to protect public health and the
- treats and disposes of the effluent at a location distant from population and protected
- enables where appropriate large scale treatment installations with combined wastewater
from many small settlements to be built and operated, resulting in considerable cost
- results in few point source rather than many scattered point and diffuse source
discharges, which are easier to manage, monitor and modify.
Sewers, Treatment Outfall
manholes, pumps Plant
Collection Treatment Disposal/reuse
Figure 1: Wastewater sanitation system components
Purpose of Document
This document is a part of the MAP MEDPOL programme and the Mediterranean
GEF Project related to Strategic Action Programme (SAP) to address pollution from land-
based activities. This series of documents-guidelines covers different issues of protection of
the Mediterranean Sea against land-based sources. This document deals with the overall
management of the wastewater sanitation system, and particularly with the problem of
wastewater treatment and disposal. It has been developed as a basis for a common
Mediterranean approach throughout the Mediterranean region.
These guidelines deal with urban wastewater and effluent from urban wastewater
treatment plants for domestic and pre-treated industrial wastes. They do not cover effluent
discharged directly into the environment from sources such as:
- storm water drains;
- septic tanks, etc.
The guidelines do not apply to cases where raw wastewater is applied to land as a
part of the treatment processes.
Wastewater treatment and discharges from treatment plants of industries are not
covered by these guidelines.
In these guidelines it is assumed that the industrial wastewater connected with urban
wastewater collecting system was pre-treated at the industrial treatment plant in accordance
with the local and national guidelines for industrial trade wastewater-effluent. The general
rule is that industrial effluent, prior to being discharged into the urban wastewater collecting
system, should have quality equal to or better than the typical domestic wastewater in order
to be transported to and treated at the urban wastewater treatment plant. Only certain higher
levels of concentration of biodegradable organic matter than domestic wastewater can be
acceptable, which has to be regulated in advance.
These guidelines are intended to apply until the next revision of this document. They
describe the principles and practice of managing effluent in accordance with the
Mediterranean context, and help identify and select appropriate methods for the
Mediterranean region. These guidelines consider and respect the generally known principles,
as well as relevant EU directives, and especially the Council Directive concerning urban
wastewater treatment (91/271/EEC). The effluent parameters of major concern, the minimum
level of treatment, and the commonly required level of treatment are indicated for each of the
discharge options. The guidelines can be applied for assessment of the existing effluent
discharges, new schemes, and proposals for effluent management. The guidelines are not
intended as a replacement for national or international regulations in this field, and especially
not for EU countries and the relevant directives.
These guidelines are intended to be used in the Mediterranean region, and particularly in
the non-EU countries in the region by:
- decision makers on the wastewater treatment, disposal and effluent management in the
- planners and designer of wastewater treatment and disposal systems;
- individuals and organisations such as: government agencies, water authorities, decision
makers, regulators, community and special interest groups involved in the preparation of
coastal areas, river basin or catchment management plans;
- those involved with different levels of the approval processes;
- as a training material for capacity building in the field;
- all others with an interest in the management of wastewater sanitation systems.
2. ENVIRONMENTAL CONSIDERATIONS
Water is essential for life. It also plays an important part in the economy of a modern
country. Ensuring that water resources are understood, respected and managed correctly is
vital for any nation future. Coping with the various demands for water, and seeking to
maintenance and improve the quality of water, is an important and sometimes difficult
Rivers, estuaries, coastal water and underground water are all integral parts of the
natural environment. Careful planning and management is needed to protect and conserve
them, and to ensure that the water they supply is suitable for a variety of uses.
Water provides important habitats for wild plants and animals. We use water for agriculture
and industry, for leisure activities- and of course for drinking.
The water we use eventually returns to watercourses and sea. Provided it is not
polluted with harmful, persistence substances, water can be used again and again. Evan so,
we do need to ensure that we do not take too much water at any one time from a river or
Waters, with the plants and animals that live in them, can dilute, disperse and break
down some materials that enter them. For a long time we have made use of this capacity,
both of coastal and inland waters, to dispose of waste. That why we must seek to ensure that
the water body and its living components are able to purify the water, and that the entry of
pollutants does not threaten water quality.
Background water quality
The water environment is a complex system controlled by a variety of physical,
chemical and biological processes. The understanding of these processes is a prerequisite of
any consideration of man’s past or future impact on water. Of particular interest in this
context is the description of the processes and their spatial and temporal scales, which are
important in different water areas and for different pollution situations.
Identification of water sensitive areas is one of important background activities for
implementation of appropriate treatment. A water body can be identified as sensitive related
to their ecological characteristics (e.g. eutrophic or potentially eutrophic waters) as well as
related to water uses (e.g. water intended for the abstraction of drinking water or food
Municipal wastewater consists of a mixture of domestic wastewater, effluents from
commercial and industrial establishments and urban runoff. Municipal wastewater
composition depends on the specific water consumption. This can vary from 50 - 300
l/capita/day and together with other than discharges from households (industry) explains the
wide concentration range of main wastewater constituents.
Municipal wastewater contains over 99.1 percent water. The rest includes material
such as suspended and dissolved organic and inorganic matter and microorganisms. These
materials give physical, chemical, and biological quality that are characteristics of municipal
wastewaters. A typical composition of municipal wastewater is given in Table 1. The values
vary with the type of wastewater collecting system used and wastewater input.
Concentrations are higher in separate systems than in combined systems. Wastewater
quality data show seasonal, daily, and hourly variations. Concentrations are also different in
wet and dry periods. For design, the actual composition of wastewater should always be
Figure 2: Municipal wastewater components
Typical composition of municipal wastewater (UNEP - GPA, 2000)
Parameter Description Range of
Qm (l/capita/day) Average wastewater flow per capita per day 150 - 250
TS (mg/l) Organic and inorganic, settleable, suspended and dissolved 300 - 1000
SS (mg/l) Portion of organic and inorganic solids that are not dissolved. 150 - 350
BOD5 (mg/l) Biochemical oxygen demand (5-d, 20 C). It represents the 100 - 400
biodegradable portion of organic component.
Total N (mg/l) Total nitrogen includes organic, ammonia, nitrite, and nitrate 20 - 85
Organic N (mg/l) It is nitrogen bound in protein, amino acid, and urea. 8 - 35
N - NH3 (mg/l) Ammonia nitrogen is produced as first stage of decomposition 12 - 50
of organic nitrogen.
Total P (mg/l) Total phosphorus exists in organic and inorganic form. 5 - 15
Organic P (mg/l) Organic phosphorus is bound in organic matter. 1-5
Inorganic P Inorganic form of phosphorus exists as orthophosphate and 4 - 10
Total Coliforms The group of aerobic and facultatively anaerobic Gram- 106-109/100ml
negative, non-spore-forming, lactose-fermenting bacteria
which typically inhabit the large intestine of man and animals.
Cl (mg/l) Chloride in wastewater comes from water supply, human 30 - 100
waste and domestic water softener.
Sulphates (mg/l) Sulphates contents in wastewater. 20 - 50
Loading of suspended and dissolved solids in municipal wastewater on a per capita
basis remain relatively stable, Table 2. The variation in constituent loading per capita per day
may be due to industries served, usage of garbage grinders and domestic water softeners,
and discharge of septage. In small treatment facilities their effects may be significant.
The population equivalent of a waste may be determined by dividing the total mass
per day by the per capita mass load.
Typical unit waste loadings
BOD5 (g/cap/d) 60 - 80
COD (g/cap/d) 110 - 160
Total suspended solid (TSS) (g/cap/d) 70 - 100
Total nitrogen (as N) (g/cap/d) 11 - 14
Total phosphorus (as P) (g/cap/d) 2-4
Total coliforms (b.c./cap/d) 1010 - 1012
Characteristics of wastewater discharges
Effluent management requires wastewater treatment to a level, which will prevent
further deterioration, secure protection and enhance the status of aquatic ecosystems,
minimise risk of human disease, and protect environmental uses/values of the waters.
Inappropriate treatment of wastewater can cause significant and irreparable damage to
receiving waters and land environments. Major threats to the environment are contaminants
such as: for inland waters primarily phosphorus and than nitrogen, for the sea waters
primarily nitrogen and phosphorus, BOD/COD, suspended solids, heavy metals and toxic
substances, pathogens. They can cause environmental damage and threat to human health,
directly or indirectly, by food chain processes.
Protection of aesthetic environmental values is necessary to avoid unacceptable
visual, odour, and taste problems, as well as other visual evidence of wastewater solids
being discharged: colour, floating materials, grease and oils. Generally, there should be no
surface slick visible and no floatable wastewater solids, especially in the bathing areas. This
can be achieved through the application of pre treatment processes, and much better, by
Faecal waste from humans and animals contains pathogen micro-organisms (viruses,
bacteria, fungi, and protozoan) which are directly harmful to human health. Water-related
diseases, such as gastro-intestinal diseases, remain among the main health concerns.
Raw wastewater contains many species of micro-organisms which determine the
potential health risk associated with recreational uses of receiving waters or consumption of
seafood. Discharged by effluent, pathogens end up in the waters. The pathogens die off
slowly in rivers, lakes and sea, and taint fish and shellfish. Rate of die off is significantly
higher in sea than fresh waters. The level to which pathogens have to be reduced to ensure
appropriate environmental values/uses is prescribed in appropriate standards.
Faecal coliforms are the most widely used indicators for likely presence of pathogens,
selected because of their ability to indicate the presence of fresh faecal material and thus the
possible source of pathogens.
The nutrients, phosphorous and nitrogen are usually present in domestic wastewater.
Increased concentration of nutrients (phosphorus and nitrogen) in receiving waters usually
leads to over-fertilisation and blooms of algae or dino-flagelates (eutrophication) which alters
the natural ecosystems. This can also in some cases cause development of undesirable
species - cyanobacteria which produce biotoxins that cause skin rashes on bathers, and can
kill animals which drink affected waters. Once these organisms die off, they start rotting and
deplete oxygen, which in turn affects all higher life forms in waters.
Acceptable levels of nutrients vary widely and must be assessed on a case-by-case
basis. A water body must be considered as nutrient-sensitive if:
- natural freshwater lakes, other bodies, estuaries and coastal waters are found to be
eutrophic or have poor water exchange;
- surface waters intended for the abstraction of drinking water contain more than the
concentration of nitrate laid down under drinking water standard.
Less sensitive areas are marine water bodies or fresh-water areas in which
wastewater does not affect adversely the environment as a result of morphology, hydrology
or specific hydraulic conditions which exist in that area. Generally, these areas have high
rate of water exchange/circulation and are not subject of eutrophication or oxygen depletion.
Toxicants in effluent, such as heavy metals (mercury, cadmium, etc.), and persistent
organic substances, such as PCBs, can influence health, either as acute or chronic effects.
Toxicants are a chronic risk to human health when they are:
- persistent in the aquatic environment:
- bioconcentrated several thousand fold;
- exerting a toxic effect after prolonged exposure to low concentrations of the toxic
The most common toxicants are heavy metals and chlorinated organic. They are of
concern in all environments. PCBs and other persistent organics can be transferred through
marine food chain to end up in the fat tissues and milk of adult seals. It is necessary to set
out a list of priority substances, on the basis of their toxicity, persistence and bio-
accumulation, which present a significant risk to or via the aquatic environment.
The appropriate approach is to control toxicants at the source. It is necessary for all
industrial wastewaters, which contain such matter. The aim is to eliminate or to reduce
pollution of water by certain dangerous substances. To do so it is necessary to set emission
standards for sewers and waters, establish system of prior authorisation, and implement
programmes to prevent or reduce pollution. Toxicants can be partly removed from
wastewater through biodegradation, or are retained in the sludge. The substances should not
be allowed to contaminate wastewater sludge to such extent that the reuse of sludge can be
The use of chlorine for disinfection is of special concern if the discharge is to water,
as the concentration present can be harmful to aquatic life. Where the discharge is to waters,
treatment techniques that do not add to the aquatic toxicity of the effluent are preferred.
Good example is long submarine outfall, which uses sea water for disinfection. Where a
chlorine is the only practical disinfection option, the need for dechlorination of the effluent
should be considered where there is not sufficient dilution through dispersion to ensure that
chlorine concentrations are below toxic levels.
Toxic inorganic chemicals, like metals, in higher concentrations may cause
synergistic or antagonistic effects in terms of toxicity in biological wastewater treatment
Dissolved solids are portions of organic and inorganic solids that are not filterable.
The impact of concentration and nature of soluble salts in treated effluent on land and fresh
waters has to be considered very carefully. Salt discharged with effluent may alter salinity of
fresh water, which may affect ecosystems, depending on the level of stress and ecosystem
characteristics. It can also affect possible uses of fresh waters.
Dissolved solids in land application must be also very carefully considered. They may
create serious environmental problems, particularly in association with higher water tables.
This is especially a problem in the case when effluent or water are used for irrigation. Even if
the concentration of dissolved salts is low it can result in a high concentration of salt in soil
and reduction in crop production.
Suspended solids originate form households and industrial waste, but also from
urban run-off. The suspended solids render river and lake waters turbid, which in turn affects
the biological productivity in water. Much of suspended solids are organic. When it settles out
in lakes, rivers and estuaries it will start rotting creating a local oxygen-poor environment with
same effects as BOD. Also, disposal of wastewater in shallow and close sea may lead to this
condition. At the same time, suspended solids are comparatively cheap to remove. It is the
logical first step to build primary treatment to remove suspended solids, and add the next
biological treatment steps later as funds become available.
In the review of each discharge all other parameters must be considered. Such parameters
are temperature, sand, pH, oils, biochemical oxygen demands, etc. Organic matter (BOD)
causes depletion of oxygen in the surface water. As a result, fish die, the water turns black
The review should assess the impact of parameters on the ecosystems and environmental
values of receiving water or land.
Box 1: Constituents in wastewater and their impacts on the marine environment
Solids High levels of suspended solids may cause excessive turbidity,
shading of seagrasses and result in sedimentation, which is
potentially damaging to benthic habitats and can cause anaerobic
conditions at the sea bottom. Fine particles may be associated
with toxic organics, metals and pathogens that adsorb to these
Organic matter Biological degradation of organic matter poses oxygen demand
and can deplete available dissolved oxygen. The strength of
wastewater is commonly expressed in the BOD parameter
(Biochemical Oxygen Demand). High BOD levels in natural waters
can therefore cause hypoxia and anoxia, especially in shallow and
enclosed aquatic systems, resulting in fish death and anaerobic
conditions. Anaerobic conditions subsequently result in release of
bad odours (due to formation of hydrogen sulphide).
Nutrients Nutrients increase primary production rates (production of oxygen
and algal biomass); adverse levels cause nuisance algal blooms,
dieback of coral and seagrasses, eutrophication that can lead to
hypoxia and anoxia, suffocating living resources (fish). Massive
die-off of algal matter will result in additional organic matter.
Pathogens Pathogens can cause human illness and possible death. Exposure
to human pathogens via contact with contaminated water or
consumption of contaminated shellfish can result in infection and
Toxic organic chemicals Many toxic materials are suspected carcinogens and mutagens.
These materials can concentrate in shellfish and fish tissue, putting
humans at risk through consumption. Bio-accumulation affects fish
and wildlife in higher food chain levels.
Metals Metals in specific forms can be toxic to various marine organisms
and humans; shellfish are especially vulnerable in areas with highly
Fats, oil and grease Fats, oil and grease float on the surface of sea water, interfere with
natural aeration, are possibly toxic to aquatic life, destroy coastal
vegetation, reduce recreational use of water and beaches and
threaten water fowl.
Environmental uses and water quality
Use area definition
The usual generalised uses of the receiving waters have been identified, and are listed in
The water uses are often specific to a particular area of the receiving waters. The
“shell-fishery” applies to shellfish beds, “bathing” to bathing beaches, “recreation” to the area
used for different water recreation activities, and so on. These areas are defined as Uses
The water use specified as “ecosystem” often applies to all areas outside the mixing
zone. However, special protecting/conserving areas have to be specified.
Waters used for drinking purposes are of a strategic interest, with the highest level of
protection needed in order to ensure sustainable long-term water use. Generally, discharges
of effluent are not permitted in these water bodies.
The drawing up of the water use area boundaries is a multidisciplinary activity
involving biologists, chemists, environmentalists, the general public, politicians and other
interested parties. These areas are generally defined by development planning processes of
Definition of the water use in the area concerned is one of the first steps in the
wastewater management planning after considering the environmental conditions.
The most sensitive selection of the Use Area is the “mixing zone” selection, which is
practically the selection of the point of discharge of effluent. The selection of this zone
requires close co-operation with the public and relevant authorities. An appropriate tool for
the selection of this zone is Environmental Impact Assessment, or similar assessment
Environmental Quality Objective and Environmental Quality Standards
The fundamental principle of the Mediterranean policy for the protection of the aquatic
and marine environments is that the standards to which individual discharges are required to
confirm should be set with reference to and objective for the quality of the water affected.
An Environmental Quality Objectives (EQO) is the requirement that a body of water
should be suitable for those uses identified by the controlling authority. The uses are
protected by one or more Environmental Quality Standards (EQS). An EQS is a specified
concentration of substance in the water body, which must not be exceeded if a given use is
to be maintained.
Inherent to this approach is the need to allow a reasonable zone in the environment
for a discharge to mix with the receiving water. The “mixing zone” is the area around a
discharge point wherein the EQS my be exceeded and some level of environmental damage
may occur. The decision as to whether or not a “mixing zone” is reasonable in size is a
matter of judgement for the controlling authority.
The most important WQO defined to protect the Uses of the aquatic environment are
presented in Table 4.
Environmental Quality Objectives
EQO Environmental Quality Description
1 Drinking water Objective is protection of consumer, by restricting levels
of substances in the water depending on level of
possible water treatment to achieve drinking water
2 Human Food Source Objective is protection of consumer, by restricting levels
Protection of substances in any food derived directly or indirectly
2a) Fisheries from fresh and saline water, or by use of water for
2b) Shellfisheries agricultural purposes.
2c) Agricultural water use
3 Fish and Shellfish Protection The objective is to preserve fish and shellfish, primarily
for commercial exploitation, and also for angling
interests, protection of an ecosystem or general
environmental management. EQO2 may also apply, but
only if the fish are eaten by humans. Protection must
extend to the most sensitive stages of the lifecycle.
4 Aquatic Protection The objective is protection of other aquatic life and
dependent non-aquatic organisms, not of commercial
interest, its food sources and/or an ecosystem. Where
necessary the sensitive stages in the lifecycle are taken
into account. If human consumption is involved, EQO2
above will also apply.
5 Industrial Abstraction Saline waters are usually only abstracted for cooling
Protection purposes, with a low quality requirement. Fresh water
can be abstracted for different uses in industry with
specific objectives and corresponding quality
6 Recreation For the protection of swimmers and those engaged in
6a) Bathing water sports and for protection of aesthetic values of
(primary body contact) the waters.
6b) Contact Water Sports
(secondary body contact)
6c) Visual use
7 Public Nuisance Prevention- This is the minimum environmental quality necessary to
Aesthetic considerations protect public health and to prevent visual and smell
nuisance. General amenity interests, such as protection
of fish, aquatic plants, bird life and so on are covered by
other objectives above.
Each use of the waters requires appropriate Environmental Quality Standards
(EQS)/water quality. For the EU countries and the acceding countries appropriate EU
Directives provide appropriate Standards. Non-EU countries generally have standards similar
to the EU directives or standards recommended by international institutions such as the
World Health Organisation, the Barcelona Convention and its Protocols, and relevant MAP
Interim Environmental Quality Criteria (MAP-IEQC).
The possible Environmental Quality Standards for waters are presented in Table 5.
They are given as minimum standards. Each country may apply stronger standards in
accordance with the specific conditions and/or international/regional obligations.
Environmental Quality Standards associated with Use Areas
Environmental EQO No. Aesthetic Physical-chemical
value/use (Table 1.) standard standard
Drinking water 1 None WHO/EU directives EU/WHO Drinking Water
Fisheries 2a, 3 None No restrictions Appropriate EU
Directives (limit for
Shell-fisheries 2b, 3 None EU Directive; Appropriate EU
MAP-IEQC Directives (limit for
Agricultural 2c, 3 None Appropriate EU or Appropriate EU/WHO
water WHO directives; Directives (limit for
MAP-IEQC selected substances);
Ecosystem 3, 4 None No restrictions Appropriate EU
Directives (limit for
Abstraction 5 None No restrictions No restrictions
Bathing 6a Presence of EU Bathing Waters Appropriate EU
recognisable Directives; Directives (limit for
solids MAP-IEQC selected substances);
Water/marine 6b Presence of No restrictions Appropriate EU
recreation buoyant Directives (limit for
recognisable selected substances);
Visual use 6c Presence of No restriction In accordance with
solids characteristics and
Mixing zone 7 Presence of No restrictions EU TiO2
recognisable No other restrictions
Legislation and role of authorities
There have been basically two different approaches to tackle water pollution problem,
and therefore approaches to wastewater management:
(i) The Water Quality Objective approach (WQO) defines the minimum quality
requirements of water to limit the cumulative impact of emissions, from both point
sources and diffuse sources. This approach, therefore, focuses on a certain quality
level of water which is not harmful for the environment and human health.
(ii) The Emission Limit Value approach (ELV) focuses on the maximum allowed
quantities of pollution that may be discharged from particular source into the aquatic
environment. This approach, in fact, looks at the end product of a process, such as
wastewater treatment, or which quantities of pollutants may go into the water.
In case of WQO approach, the level of wastewater treatment and method of disposal
of effluent have been selected to achieve required water quality objectives of the receiving
waters/sea body with the most appropriate method/solution (economically and
technologically). It means that the level of the wastewater treatment has to be regulated on
the basis of characteristics of the wastewater (source of pollution) and prescribed water
quality objective of receiving water body.
In case of ELV approach level of the wastewater treatment and method of the effluent
disposal are prescribed directly or indirectly (by allowed quantities of pollutants that may be
discharged) by appropriate regulations in accordance with the characteristics of the particular
point source of pollution.
There has been a long scientific and political debate about these approaches. As a
result, recent legislation of many Mediterranean countries, as well as of the European Union,
is based on a “combined approach” where WQOs and ELVs are used to mutually reinforce
each other. Such approach has to be used in the Mediterranean region too. In this concept,
the more rigorous approach will apply in any particular situation. This combined approach is
in accordance with the precautionary principle, and the principle that environmental and
health damage should, as a priority, be rectified at the source, as well as the principle that
environmental conditions in particular regions shall be taken into consideration. It means that
the Mediterranean regional environmental conditions, as well as the environmental
conditions of various sub-regions (countries) in the Mediterranean, have to be considered.
The “combined approach” to pollution control requires:
- limiting pollution at the source by setting emission limit values or other emission
- establishing water quality standards (objectives) for water bodies receiving effluent and
permissible water uses.
In each case, the more stringent approach will apply. In this case, the country have to
set down both the measures to limit values to control emissions from individual point
sources, and the environmental quality standards to limit the cumulative impact of such
emissions as well as diffuse source of pollution.
In this approach, the level of the wastewater treatment and method of disposal of the
effluent are directly or indirectly prescribed by appropriate regulations. It has to be done in
accordance with the characteristics of the particular source of pollution (emission limit value),
and in accordance with the prescribed water quality objective and permissible uses of the
receiving water body (required environmental quality standards). The stringest limit values
apply for discharges into freshwaters prescribed for drinking purposes followed by uses like
swimming, recreation etc.
Successful implementation of this concept requires, among others, an appropriate
control system. Achievement of such degree of control require that the competent authorities
have sufficient legal power and resources to be in a position to:
- identify and monitor all types of discharges and other impacts in the catchment area;
- grant permits for the discharge of effluent and enforce compliance with permit conditions;
- undertake pollution prevention activities such as: enforcing protection zones, or
controlling activities which could have adverse impacts on the state of water and sea.
Specific environmental objectives or emission limit values have to be set for the
relevant pollutants and pollution sources of priority concern substances (“priority
substances”) such as: mercury, cadmium, hexachlorocyclohexane (HCH), DDT, PCP,
choloform, aldrin, dieldrin, cyanides, metaloids and metals, etc.
Waters used for drinking water abstraction have to be subject to particular protection.
For each significant body of water that is used for abstraction or that may be used in the
future, an appropriate set of environmental quality standards has to be established.
The most important element of the sustainable wastewater management system is
the balance among the three critical and interrelated aspects: (1) water quality, (2)
investment, and (3) tariffs. The objective water quality standard and target levels for
wastewater treatment should be defined. These quality standards should then determine the
investment required for achieving water quality objectives. Finally, the investment level drives
the tariffs, which aim to recover the cost. These tariffs, in turn, determine the service level
which can be provided, and the associated water quality objectives. If the balance does not
exist, the designed water quality objectives will hardly be achieved.
Role of authorities
General trend in today’s national regulation systems is to clearly identify and separate
the roles of:
- water resources management;
- regulation; and
The central government institutions have to properly distribute responsibilities among
different national ministers and/or regional and local authorities, necessary for successful
implementation of the strategy for sustainable water resources management. The key
questions, which should be addressed, are:
- Decide on the “lead” institution for implementing the Strategy, as well as for ensuring the
co-operation and decision-making process in case of other ministers being involved. In
general, ministries that will be involved are: Ministry of the Environment (water quality
standards, emission limit values), Ministry of Health (drinking water, use of treated
wastewater), Ministry of Agriculture and Forestry (use of sludge, pollution); Ministry of
Industry (emission control), and Ministry of Foreign Affairs (transboundary pollution).
- Decide on the distribution of responsibilities (legislation, implementation) among national,
regional and local bodies;
- Arrange for the involvement of other public bodies and agencies (institute, environmental
agency, water agency, water/environmental inspectorate, etc.)
- Decide, design and implement a national plan for water protection.
The competent national authorities are generally responsible for:
- Planning and implementation activities, including setting clear water quality goals and
emission limits values which integrate environmental and economic considerations, with
the full participation of stakeholders and consideration for community views;
- Regulation addressing duplications and gaps in government and sectors responsibility for
water and wastewater regulation;
- Putting in place clear accountabilities and establishing management for water resources;
- Meeting the community’s legitimate demands for input into decision making processes;
- Establishing an inspectorate authorised to inspect installations and monitor management
practices and water quality against objectives.
The role of regional and local governments in the water sector is important because:
- In many countries they have administrative structure in which certain powers are
devolved to the regions or local level of government (planning authorities, municipality);
- Modern concept of water management is based on decentralisation of catchment or river
basin, and involves local people as much as possible in the planning and decision
- Needs of the co-operation of regional and local authorities in developing operational
objectives which are also use-related (water for bathing, water for aquaculture, water for
drinking water abstraction, water for irrigation, etc.).
- The provision of water and wastewater services is the responsibility of the regional or
- The responsibility for the construction of water and wastewater treatment plants, water
pipelines and sewer networks.
The responsibility for ensuring that drinking water is safe and that human waste
products are disposed of in a satisfactory way so as to minimise public health risk.
Monitoring is an essential part of the implementation of the water legislation.
Systematic monitoring of surface water and ground water quality and quantity includes:
- surveillance monitoring;
- operational monitoring;
- investigative monitoring; and
- compliance checking.
Proper co-ordination of monitoring contributes to achieving the environmental
objectives, but also reduces the administrative and financial burden of monitoring.
The monitoring in general has to be established for:
- discharges of wastewater, for parameters depending on the particular case;
- surface waters, for ecological, physical-chemical and morphological parameters;
- groundwater, for physical-chemical parameters;
- bathing water (fresh and marine) during the bathing season, for bacteriological and
- drinking water, for bacteriological and physical-chemical parameters;
- re-used water, for bacteriological and physical-chemical parameters.
Reporting is one of the most important elements necessary for progress tracking
good public relations and information. The competent authorities must have the power to
collect information and their duties should include the requirement to set up a data collecting
and reporting system. This can be achieved through requirements for licensed wastewater
discharges to report information to the competent authority on the activities to which the
license permit relates.
3. MANAGEMENT FRAMEWORK
Aims and Objectives
The objective of wastewater management is to avoid long-term deterioration of fresh
and coastal sea water quality by appropriate treatment of wastewater and disposal of effluent
aiming at sustainable protection and uses of fresh and sea water resources. Thus, the basic
aim of wastewater management is to return treated wastewater to the environment in a way
which the community accepts after considering both environmental and cost factors. The
objective of wastewater management include:
- avoiding health risks;
- preventing the degradation of the aquatic environment;
- promoting sustainable water uses;
- minimising both adverse impacts to land and contamination of surface and ground waters
when used in land applications;
- maintaining the agreed water quality objectives for receiving waters when discharging to
surface waters and sea;
- maximising the reuse of treated wastewater considering both the value of water and the
The water quality objectives will usually be decided after considering:
- existing ecosystems;
- existing state of waters and water quality trends;
- the environmental uses/values of the receiving water;
- uses of the receiving waters;
- environmental flows (biological minimum flow);
- other community objectives.
Quality objectives apply to bodies of water and are related to ambient conditions, and
are also based on the toxicity, persistence and accumulative characteristics of substances.
Strategy and Principles
Ecologically sustainable development includes the enhancement of individual and
regional well being by economic development, which balances economic, ecological and
social demands, and safeguards the welfare of future generations.
This concept of ecologically sustainable development considers a more global
approach to a water policy based on integrated river basin/catchment management. River
basin and catchment areas, including coastal catchment areas, are the most appropriate
defined geographical areas for the water resources management and coastal sea
management. This enables assessment of all activities, which may affect a watercourse, the
associated estuary and coastal sea, and their control by measures which may be specific to
the conditions of the river basin/catchment area.
This concept of catchment management embraces:
- comprehensive approach to natural resources management within a catchment area with
the water quality considered in relation to land and water uses, characteristics of aquatic
and riparian ecosystems, and other natural resources;
- co-ordination of all the agencies, authorities, water users, water providers, and interest
- extensive opportunity for consultation and participation.
A comprehensive strategy for achieving sustainable water quality management in the
Mediterranean region has to be based on a set of principles, such as:
- High level of protection;
- Precautionary principle;
- Prevention action;
- Rectification of pollution at the source;
- Polluter pays principle;
- User pay principle ;
- Waste hierarchy approach (prevention, minimisation, treatment/disposal); and
- Integration of environmental protection into other national policies (transport, agriculture,
energy, tourism, fishery, etc.)
Most important control mechanisms are regulations and economic tools. Regulation
of water in the Mediterranean region varies from State to State. The regulations adopted at
the regional Mediterranean level include the Convention for the Protection of the
Mediterranean Sea Against Pollution (Barcelona Convention, 1975); Convention for the
Protection of the Marine Environment and the Coastal Region of the Mediterranean
(Barcelona, 1995) and the related protocols. One of the most important for this subject is the
Protocol for the Protection of the Mediterranean Sea against Pollution from Land-Based
Sources (Athens, 1980/1996).
Legally binding for the Mediterranean region are UN and other international and
regional conventions, protocols, and agreements, such as: Agenda 21 (Rio, 1992),
Convention on Protection and Use of Transboundary Watercourses and International Lakes
(Helsinki Convention, 1992); Convention on Environmental Impact Assessment in a
Transboundary Context (Espoo, 1991/1998); Convention on Public Participation (Aarhus,
1998), and others.
However, for the EU countries and the acceding countries there is a set of EU
Directives and the appropriate EU policy on the water management and protection, which
have to be applied. Water is one of the most comprehensively regulated areas of the EU
environmental legislation. The new European Water Policy has been developed, as well as
its operative tool, the Water Framework Directive (2000/60/EC). This Directive provides a
managerial framework for the whole range of water protection policy and legislation. The
most important directives for wastewater companies and thus for these guidelines is: Council
Directive concerning urban wastewater treatment (91/271/EEC).
Discharges should normally comply with regulations, such as:
- Health Department regulations;
- planning regulations;
- catchment/river basin regulations;
- environmental/water authority works approval;
- environmental/water authority discharge licences;
- pollution control.
In order to achieve the water quality objectives the measures put in place must be
properly implemented and enforced. This can be achieved by developing a suitable
regulatory regime with adequate resources to implement and enforce the law. Regulation in
this sector, in general, involves the following activities:
- authorisation and/or permitting;
- monitoring, inspection and enforcement;
- data collection and reporting.
The principal tasks related to authorisation and permitting is:
- issuing permits for discharges to water and sea, including quantity and quality of the
discharge, setting emission limit values and ensuring compliance with the water quality
- issuing permits for the abstraction and use of water and sea, bearing in mind the principle
of long-term balance between abstraction and natural recharge, environmental needs
and competitive uses of water/sea body.
In setting conditions, the competent authority may have to take account of the
interests of other statutory bodies and others who may be affected by the discharge or
activity through consultation. The details of the permit must be available to the public in some
readily accessible form.
The uses of economic instruments are a part of a programme of measures for
sustainable water quality management. The principles of recovery of the costs of water
services, including environmental and resources costs associated with damage or negative
impact on the aquatic environment, have to be taken into account in accordance with
polluter-pays and user-pays principle. This means that anyone whose action pollutes or
adversely effects the environment should pay the cost of the remedial action. The application
of economic tools cannot currently replace the regulatory approach to combat pollution. It
should be seen as a part of an integrated system of incentives and regulations where price
driven forces such as costs for water use promote preventive measures in households,
industries and thus reduce the wastewater quantities and relevant costs for treatment and
disposal. Market based instruments rely upon market factors to change the relative price of
goods and services, which in turn modifies the behaviour of public and private polluters so
that environmental protection or improvements can be achieved. In so doing, have regard to
the social, environmental and economic effects of the recovery, as well as the geographic
and climate conditions of the Mediterranean region or sub-regions affected.
The main instruments of cost recovery are:
a) Pricing: Wastewater tariffs or charges which cover the cost of the collection plus
treatment, and this can include organisations to bring in recycling or reuse.
b) Pollution charges: Effluent charges based on actual quantities and/or pollution loads of
effluent or on some surrogate, though they need to be set at a realistic level to encourage
reduction in effluent production. The collected money can be used to fund operating cost
and loan charges for capital investment. Administrative charges, which are used only to
cover the cost of operating the regulatory system.
c) Tradable permits: The responsible authority sets a limit on the total allowed emissions of
pollution, and allocates this amongst the sources of pollution by issuing permits to emit a
stipulated amount over a specified period of time. After the initial distribution, permits can
be bought or sold. Trade can be external, between different organisations, or internal,
between different installations within the same organisation (restricted use in accordance
with specific situation).
d) Subsides: Subsidies include tax incentives, tax credits, grants and low-interest loans.
e) Deposit-refund systems: Customers pay a surcharge when buying a potentially polluting
product. On returning to an approved centre for recycling or disposal their deposit is
f) Enforcement incentives: These are penalties to induce polluters to comply with
environmental standards or regulations. They include fines (for exceeding limits),
performance bonds (payments to regulatory authorities before a potentially polluting
activity is undertaken, which is returned when the correct regulatory levels are met), and
liability assignment (where polluters are made liable for any environmental damage they
Any wastewater programme needs to address financing and cost recovery for
sustainable sanitation schemes and ensure equity as much as possible. Unfortunately, users
are willing to pay only for what they see as a benefit or priority. Usually it is not sufficient to
pay the full cost of the systems, including collecting system and treatment. Complementary
financing has to be secured through a variety of taxes presented above. However, tax
collection in some developing countries is not efficient, and in addition significant part of
population does not pay taxes at all. It is often the reason why the wastewater management
is insufficiently effective.
The concept of “full economic cost recovery” can and will provide an adequate signal
only when the following are met:
- There is a clear relationship between the water use (pollution) on one hand, and the
costs of providing the necessary services, and environmental cost on the other, and it is
possible to put monetary value on these costs;
- The institutional framework enables governments to charge the polluter, and there is a
political “willingness to charge”, which again depends strongly on the social and
economic context and the public “willingness to pay”.
Two procedures have been used to identify appropriate levels of effluent quality:
1. Effluent management and environmental values/water uses;
2. Technology based guidelines.
Effluent management and environmental values/water uses
The underlying principle of managing effluent discharges is maintaining the
environmental values and uses (Box 2.) of waters and sea, and for land application, the
sustainable use of land. Environmental values or beneficial use are values or uses that
promote public benefit, welfare, safety or health, and ecosystem protection, and are in need
of protection from the effects of pollution, waste discharge and deposits. Environmental
values or beneficial uses within a catchment and coastal sea have to be defined by balancing
the social, environmental and economic benefits and costs. This is generally the
responsibility of the State or regional governments, and should be defined through the
development of the river basin management plans which have to be drawn up on a river
basin basis, considering land-use plans and other sectoral development plans. It may be
necessary to sub-divide a larger river basin into smaller units (catchment), and sometimes a
particular water type may justify its own plan (e.g. coastal sea catchment area).
The adoption of environmental values/uses has to be based on balancing financial
costs and environmental benefits. The balancing should consider all local and specific factors
of the catchment/coastal sea area, such as urbanisation, growth and development, and
waste management practice. The goal is to achieve ecologically sustainable development,
which can be done only by optimising these factors in the process of development of the river
basin/catchment management plans.
Application of water quality based effluent standards should take into account the
relative contribution of diffuse sources and background waters/coastal sea conditions to
ensure the achievement of the good state of the fresh and marine waters, and thus of the
required environmental quality standards.
Box 2. Environmental values/uses
Environmental values for the aquatic systems are:
Protection of aquatic ecosystem
- Protection of freshwater ecosystem
- Protection of marine ecosystem
Protection of habitats and species directly or indirectly depending on water
Recreational water quality and aesthetic
- Primary body contact (swimming, surfing, etc.)
- Secondary contact (boating, fishing, etc.)
- Visual use
Raw water for drinking water supply
- Raw water subject to coarse screening only
- Raw water subject to coarse screening and disinfection
- Raw water subject to other treatments
Food production in freshwater and sea
- Production of shellfish
- Production of fish
- Production of other edible organisms
Agriculture water uses
- Stock watering
- Farmstead use
Industrial water quality
- Heating and cooling
- Hydro-electric power generation
- Textile industry
- Chemical and allied industries
- Food industries
- Beverage industries
- Iron and steel industries
- Tanning and leather industries
- Pulp and paper industries
- Petroleum industry, etc.
Effluent guidelines are to be based on the application of an appropriate and accepted
modern technology. A large variety of conventional and non-conventional wastewater
treatment technologies exists, ranging from simple screening and settling operations to
sophisticated biological and chemical operations. Wastewater treatment products, besides
adequate effluent, consist of the material removed as sludge and other residual matter. This
removed material requires additional treatment and appropriate disposal. As a rule, the
treatment costs, energy and sludge production increase with increasing pollution removal
capabilities. Effluent guidelines have to consider:
- technology that has demonstrated a consistent achievement of acceptable protection of
the receiving water/sea, or contaminant levels in the environment while maintaining
economically viable operations (“best available techniques” and “best environmental
- sludge management requirements based on local possibilities;
- time limits for installation in both new and existing plants;
- local experience, skills and knowledge for design, construction, operation and
- conditions that may affect sustainability of the management/operation;
- nature and volume of the wastewater concerned;
- engineering and scientific developments in wastewater treatment, and economic
feasibility of such techniques;
- opportunities for waste minimisation/prevention;
- the potential of new and emerging technologies to economically achieve higher levels of
These guidelines are also necessary in the case where technology-based guidelines
can produce ambient water quality above the state objective in order to cope with possible
future requirements (discharges).
Determination of effluent quality
Effluent quality has to be determined in accordance with the national legislation in the
field. A prerequisite of sustainable wastewater management is the determination of the
required effluent quality in accordance with the selected environmental values/water uses of
the water/sea bodies and their sensitivity to adverse effects on the environment, such as
eutrophication or increased concentration of nitrates in drinking water. When adopting action
plan and measures, it is necessary to take into account the best available techniques and the
best environmental practice. On the basis of the EQS it is necessary to establish and/or
implement (i) emission controls based on best available techniques or (ii) the relevant
emission limit values.
The technology-bases guidelines have to be applied progressively to the existing
installations. New installations would generally comply at start up. The existing installations
would be expected to adopt phase-down programmes to progressively bring their discharges
into compliance. However, in case of non-existence of a complete collecting system of the
agglomeration, treatment installations have to comply with the requirements progressively in
accordance with the quantity of wastewater and/or pollution loads.
If scientifically/technologically based effluent criteria are not sufficient to meet well
defined water quality criteria, then waste prevention/minimisation measures should be
applied, in order to remove the “difficult” pollutants before wastewater treatment and effluent
discharge into receiving water. This approach should be applied at the planning or design
stage of new installation, and used as the target for any planned major augmentation of the
It is necessary to determine, in co-operation with local and regional authorities, the
current state of the existing collecting system and wastewater treatment plants, and identify
those, which need an additional sewers to collect wastewater, and the provision of a
wastewater treatment plant.
In particular situations it is possible to apply “appropriate treatment” underlining that
such treatment has to ensure the necessary quality of receiving water/sea - WQS.
Receiving Water Body and Aquatic Ecosystem Protection
The eco-classification is necessary for the management of waters and sea. It will
provide general framework for determining aquatic ecosystem management objectives and
the resulting guidelines for water quality and physical habitat.
The receiving water aquatic ecosystem has to be classified in accordance with the
ecosystem characteristics. Unfortunately, there is no unique scheme for the categorisation.
The aquatic ecosystem can be generally classified in two major groups:
fresh water system, and
marine water system.
Where appropriate, each of these is further subdivided forming four broad classes:
- upland rivers and streams;
- lowland rivers.
- lakes and reservoirs;
- open (drowned river valley)
- closed (barrier or island)
coastal and marine
- barrier lagoons or embayments;
- open coast.
The EU Water Framework Directive (Annex XI) divided the waters of Europe in
ecoregions. The transitional and coastal waters of the Mediterranean region belong to the
ecoregion-Mediterranean Sea, while the rivers and lakes belong to several ecoregions:
Iberic-Macaronesian region, Pyrenees, Dinaric western Balkans, Hellenic western Balkans.
The basis for the protection of an ecosystem is the ecosystem conditions and
recommended threshold levels of acceptable change for each.
Three ecosystem conditions are recognised:
1. High conservation/ecological value systems.
These are highly valued ecosystems such as in national parks or in remote and/or
2. Slightly to moderately disturbed systems.
The biological communities remain in a healthy condition and the ecosystem integrity is
largely retained. These are ecosystems in which biological diversity may have been affected
adversely to a small but measurable degree by human activity.
3. Highly disturbed systems.
These are measurably degraded ecosystems of lower ecological value. It means that these
systems are under significant human pressure, and that for practical reasons it may not be
feasible to return them into one of higher categories/conditions.
A level of protection is a level of acceptable change from a defined reference
condition (defined from reference sites). However, appropriate level of protection has to be
based on the community’s long-term desires for the ecosystem.
Different stakeholders participate in wastewater management. The most important
1. Governments - implementation and maintenance of compliance with policies and
legislation in the field, provide environmental/wastewater agencies with authority,
reporting and response to the community.
2. Environmental agencies working on behalf of the central government - provision of
planning, setting standards and regulations, application of standards and regulation,
monitoring and compliance assessment, and technical assessment.
3. Regional and local governments/municipalities - provide input to the system and may be
affected by the decisions of agencies/government and of the wastewater authorities,
construction of public owned collecting system and wastewater treatment works.
4. Wastewater company/authorities (public and/or private)- managers of wastewater
sanitation systems, constructors and operators of privately owned wastewater treatment
5. Industrial companies - compliance with permits for effluent discharged.
6. Public - involvement in consultation processes for the planning. Reporting pollution
7. Environmental and consumer NGOs - lobbying on behalf of the public with respects to
water quality objectives, setting treatment plants, pollution problems.
8. Research institutions and universities - technical research into environmental quality
standards, toxicity assessment, water analysis, treatment technology development.
The Role of the Wastewater Company/Authority
The wastewater company/authority can be public and/or private. They act for the
shareholders, customers and the community they serve. Their roles include:
- managing the wastewater sanitation system as efficiently as possible;
- maintaining and encouraging community participation in different issues;
- informing the community about the results and impacts of its decisions;
- participating in a comprehensive catchment/river basin management approach and
- identifying the financial, environmental and social costs of decisions for the community;
- advising government agencies on technical issues and options available;
- maintaining close liaison with government agencies/authorities on the performance of the
wastewater collecting system and treatment works;
- informing and providing returns for its shareholders.
An important aspect of the wastewater management is the need to involve the public.
For many years, the responsibility for environmental decisions, and thus for wastewater
management, was taken by governmental an/or by wastewater authorities and other
agencies and water authorities. The community now expects to be involved in the decision-
making process because much of what is decided will have a direct impact on people’s lives.
Impacts include the quality of waters in their neighbourhood, costs of water and wastewater
services. Since the emission limits influence industry and end-uses such as bathing, fishing
and aquaculture farms, the public has also strong and legitimate interest in setting water
The policy-making process must provide the community with:
- information on the benefits, costs and environmental and public health impacts of
alternative methods of effluent management;
- opportunities to participate in decision making.
Public involvement in decision-making will encourage the community to consider
effluent and waste management options in a broader water resource management context. It
will ensure that community consider and be more interested in options in a broad catchment
context rather than on more narrow grounds, which can result in more sustainable
wastewater management: higher water quality, lower investments and lower tariffs. To
achieve this it is necessary to make information widely available and provide opportunities for
public involvement in decision making.
Most of wastewater services in the Mediterranean countries are publicly owned
monopolies. The cost of pursuing higher water quality results in intensive wastewater
investments and recurrent terms and must either be passed on as higher charges or
absorbed as lower returns. The cost of operation and maintenance of those wastewater
sanitation systems is often higher than the annual depreciation of the investment. Only a few
(developed) countries in the region manage to recover all costs directly from their customers
through user charges. There is a role for the local community to have a say about balancing
the costs and benefits to achieve improvements in water and sea quality, or reductions in
environmental impacts of wastewater flows, at the least cost to society and a maximum value
Costs of wastewater management programmes are very high in both capital and
recurrent terms, and those programmes depend critically for their success on effective
advocacy and public awareness through information, education and communication. That
way the process must be open to a systematic community scrutiny to ensure benefits and
justify the cost.
The ultimate decision on the discharge quality to be met lies with governments in their
roles as standard setters and regulators. The aim of public involvement is to achieve waste
management solutions that reflect the community preference on its use of resources.
It is very difficult to quantify all the costs and benefits of wastewater management.
The comprehensive cost-benefit analysis approach has substantial merit in determining
standards. However, the benefits of improved environmental amenity are very difficult to be
quantified in monetary or other terms. In particular, it is very difficult to reflect the benefits of
long-term environmental sustainability in traditional cost-benefit analysis.
This means that it is necessary to consider a wider range of assessment techniques,
which ensure that informed decisions are made. Some of the approaches which should be
used to explain and make transparent the costs and benefits of various options include:
- Establishing programme of communication with community and reporting the views
expressed via community input processes;
- Identification and determination of the issues, and presenting evidence about the nature
and scope of the identified problem (e.g. current situation with regard to wastewater
management, current knowledge and scientific evidence, evidence of recreational and
commercial use of receiving waters, evidence of existing reviving water quality, etc.);
- Providing the context within which the proposed options have been developed (e.g.
description of previous attempts to solve the problem, relationships to the wastewater
authority’s capital investment programme, existing regulatory regime, etc.);
- Assessment of current know-how, attitude and practices, and providing information on
the relevant trends and options (e.g. present knowledge in the field of the waste
management, the range of available waste management options, etc.);
- Risk assessment and sensitivity analysis;
- Environmental impact assessment;
- Calculating and presenting the total capital and recurrent costs of pursuing various levels
of environmental enhancements, and equating these to an annual cost or rate that the
individual must meet;
- Assessing the range of possible environmental and other benefits that might flow,
quantifying these where possible;
- Consulting the community on the level of enhancement it wishes to accept.
These as well as other approaches for community consultation will result in a sound
understanding of community preferences. People tend to change when they understand the
nature of change and view it as beneficial, and when they feel that they are part of the effort.
That way they have to be informed and convinced. Unless their circumstances are taken into
account and their felt needs are met no effort for change will be successful.
Failure to undertake such a process can result in:
- adoption of solution or elements of solution that the community does not support (e.g.
type of the wastewater collecting system, level of treatment, location of outfall or
treatment plant, etc.);
- investments and tariffs which community can not support;
- excessive and for public undesired exploitation of the environment;
- communities incurring high cost for what may be low priority environmental goals;
- non-sustainable wastewater management, etc.
4. OPTIONS FOR EFFLUENT MANAGEMENT
Options of the wastewater management have to be based on the philosophy,
objectives and principles presented in the previous chapter - Management Framework. Each
country in the region has some specificity related to wastewater management as a result of
cultural, environmental, political, economic and other factors, and thus needs to have a
specific list of sustainable options. However, general philosophy, objectives and principles
have to be respected because they are part of global and regional policy of sustainable
development and water resources management.
Wastewater management options should address the management of the wastewater
sanitation system as a whole (users/wastewater, collecting system, treatment and disposal)
and each of the aspects individually.
The general aspects are:
managing of collecting system;
managing of treatment system (wastewater and sludge);
effluent discharge to:
- coastal waters,
- inland waters.
marine disposal system.
Choice of preferred options is made after considering:
public health and environmental impacts;
social needs and community expectations;
regional and state ecologically sustainable development policy;
associated river basin/catchment management policy and plans;
national, international and regional obligations;
feasibility- technical, operational, financial, social and environmental criteria, options and
cost of the scheme and social impact;
available and feasible technology.
In the selection of the options it is necessary to apply a hierarchical approach for
waste management by encouraging wastewater producer, services providers and authorities
to choose waste management options towards the top of the hierarchy, as follows:
1. no use or production of unwanted substances;
2. waste minimisation or reduction of waste production quantities;
3. re-use and, thus decrease of the amount of waste to reach the environment;
4. recovery and convert;
6. dispose and disperse.
It is important to understand that most of the water used in household/town is a
transport medium for waste out of town. The one of the function of the water used in
households is to remove unwanted matter from the location where the water is used: toilets,
wash basins, kitchen sinks, washing machines, etc. The function is to clean the thing, the
fabric, the place, etc. In doing it so the effect is that the matter that is removed is transported
away with the water.
Waste minimisation is the one of the priorities of any sustainable wastewater
management strategy and should be first addressed. Waste minimisation means risk
minimisation. It is the activity at the top of the “waste hierarchy” approach.
The application of good waste minimisation practices will push the volume of
wastewater and quantity of potential pollutants to a minimum, and thus the risk to the human
health and the environment.
The most important areas that have to be considered are:
1. Reduction of contaminants in industrial wastes discharged to the collecting system (good
trade effluent characteristics);
2. Reduction of contaminants in wastewater from small industrial enterprise in towns where
it is difficult to implement the trade effluent standard;
3. Minimising of wastewater flows by applying water conservation and demand
management principles to industrial, commercial and domestic customers;
4. Management of domestic products that may add contaminants to the wastewater flow;
5. Management of collecting systems to exclude infiltration and stormwater;
6. Control, at the country level, of product constituents (organic matter, metals), and
especially home and industrial dumping of chemical substances.
Reduction of the quantity of the pollutant being discharged to the wastewater system
also has a positive impact on the entire system, such as: savings in treatment plant operation
cost and resources used, reduction in sludge production and costs of sludge treatment and
disposal, maintenance cost of collecting network and treatment plant, etc.
A reduction has direct impact on the capacity of the system as a whole, which can be
appropriately smaller, as well as the relevant investment and operational costs. However, the
most positive aspect of the reduction is minimisation of the negative impact to the
A range of actions in different areas can be applied for waste minimisation, and at
different management levels. Usually, actions in the areas are:
reduction of inappropriate use of potable water as transport medium in sewer, or
reduction of reliance on water as transport medium for waste: water saving rules, such as
requiring the use of water saving devices (showers, toilets), and pressure reduction;
incentives, such as quantity and quality based charges for major industrial and
commercial discharges, and user-pays for domestic wastewater;
education, such as providing information on the use of water-efficient appliances and
environmental friendly products and practices;
regulation, control or ban of use/import/production of certain type of products, devices
education on and promotion of on-site recycling of materials;
on-site treatment and reuse.
The usual measure for control and reduction of industrial and commercial wastewater
discharge to the communal wastewater collecting, treatment and disposal system is the
application of Trade Effluent Discharge Standards. It is a very efficient measure that leads to
waste minimisation activities at the source. It is well known that actions at the source are the
most productive for the waste minimisation. It will result in waste prevention activities,
internal recycling and reuse, and local treatment of wastewater.
The most common waste minimisation measures, which can be employed in
domestic, commercial and industrial situations, are presented in Table 6.
Waste minimisation measures in domestic, commercial and industrial situations
Domestic minimise water usage and discharge through legislation and public education, e.g. :
dual flush (6/3) toilets, low flow shower heads, low water use washing machines
and dishwashers, systematic repair of leak
bans on the use of westwater systems for the disposal of drainage water
detect and remove illegal connections, such as roof drainage
minimise pollutant loads via public education on not using the wastewater
collection system as a rubbish disposal system, limiting the amount of oil and grease
going down the sink, minimising the amount of soaps and detergents used, including
possible alternatives; and regulation of product constituents (for example,
phosphorus in detergents).
supporting and enforcing restrictions or bans on the use of sink garbage grinders
minimising the amount of household chemicals in wastewater by educating the
community on their proper disposal and by having proper disposal available, e.g.
programmes aimed at cultural change; separate the toilet waste where appropriate to
agricultural use; divert where appropriate, kitchen waste to solid waste, or to recycle.
minimise water usage, discharges and pollutant loads through a combination of
legislation, education and financial incentives (for example, a charge for service
based on the strength and volume of trade waste).
Managing the Collection Systems
The wastewater sanitation system is an integral part of the urban society. The
objectives of that system are to protect and to maintain the health and safety of communities,
to protect the natural environment and to be sustainable. There is strong interaction between
these three objectives and that way they have to be considered integrally.
To be sustainable, an urban drainage should:
be efficient and cost effective;
maintain an effective public health barrier and provide sufficient protection;
avoid local and more distant pollution of environment (air, land, and water);
minimise the utilisation of natural resources (water, energy, materials);
on-going operation of the system is necessary;
be operation in the long-term and adaptable to future requirements;
be practicable within the social context of the community that is expected to use the
the chosen technology is in balance with the available infrastructure, institutions, human
resources and economic conditions.
The system will only be truly sustainable if its financing is compatible with the long-
term ability and will of the community to pay for it.
A properly managed system will:
minimise potential for incidental spills to the environment;
minimise potential for overflows and restrict occurrence to situation where they cause
minimise odour and gasses emissions;
minimise infiltration (leakage of groundwater into the pipes and channels), inflow of storm
water through sewerage elements (manholes), and illegal discharges of stormwater to
keep wastewater volumes to a minimum;
deliver wastewater quicker and so as fresh as possible to the treatment plant so that it is
easy to treat;
minimise energy and other resources usage;
avoid deposition and blockage in the sewer;
avoid any contact of humans and animals with wastewater.
Box 3: Indicators of sustainability for urban wastewater sanitation systems
Possible indicators for urban wastewater sanitation systems are:
Wastewater Dimension Indicators
Wastewater Production Wastewater production per day
Treatment performance Removal of BOD5, P, N, S.S., COD (%)
Loadings to receiving waters Loadings of BOD5, P, N, S.S., COD (kg/day)
Resource use Chemical use per P removed and effluent
disinfected (in case chlorination)
Energy use Energy use per BOD5 and N removed, and
effluent disinfected (in case UV)
By-products Sludge production Sludge production per day
Sludge use Amount of sludge disposed or reused (%)
Recycling of nutrients P and N recycling
Quality of sludge Cd, Cr, Cu Hg, Ni, Pb, Zn content in sludge
Energy use Energy use per treated sludge
Energy recovery Energy recovered, heating and power (Gwh)
Resource use Chemical use per treated sludge
Transportation Transportation needed for ultimate disposal of
Managing the Treatment Systems
The developed environmental legislation, with respect to effluent standards, requires
adequate implementation activities, such as the construction of a wastewater collection and
The selection of a wastewater treatment technology process should consider the
average performance of a technology:
- reliability: under variable wastewater flows (especially due to seasonal tourism) and
contents, and operational problems;
- institutional manageability: planning, designing, construction, operation and maintenance
- required investment costs: generally, analyses of two major alternatives have to be
considered, land-intensive treatment systems and energy-intensive treatment processes;
- required operation and maintenance costs;
- local availability of skilled manpower.
Final technology selection also requires a detailed assessment of other pollution
sources, further projection of population size and waste production, community and cultural
characteristics, and financial capacity of the community.
A good plant operation is most important for the achievement of desired effluent
quality, and should be environmentally responsible and sustainable. In addition to presented
in designing and operating the plant to meet the effluent and sludge management
requirements, the following also must be considered:
- balancing energy usage and performance (use of low-intensity energy systems, energy
efficient aeration systems, use of methane for heating and energy recovery at the plant,
- recycling of effluent, where appropriate, for the plant operation and maintenance and
washing and watering environment;
- minimising environmental impacts: odours, noise, vibration, insect nuisance, fire hazard;
- minimising aesthetic impact (visual appearance);
- minimising hazards to the health of the staff and the neighbouring communities;
- judicious use of chemicals;
- minimising overflows and incidental spills;
- removing solids to maintain the quality of the effluent;
- developing effluent and sludge (biosolids) as resources;
- solids disposal (screenings, grease and oil, grit and sand, biosolids sludge cake);
- conformity with the existing planning decisions and development plans.
Effluent reuse serves an important function in water resources management by
providing a means to produce a quality source of water for irrigation, industrial, and urban
water requirements throughout the region. With many countries facing severe water
shortages, reusing water for irrigation and industrial purposes is gaining ground. It is
application of effluent in a way that also provides income, reduces costs and leads to some
other benefits. Directly or indirectly, it could result in economic, social and environmental
Effluent is a product of water abstracted from resources, so if the effluent is not
returned to the natural inland water bodies, the flow in rivers is reduced. It has to be analysed
carefully in areas lacking water.
In addition to providing a low cost water source, other benefits include increase in
crop yields, decreased reliance on chemical fertilisers, and protection form the frost damage.
However, presence of pollutants should be recognised. Less obvious characteristics, such as
elevated levels of dissolved solids and changes in water chemistry can be significant in both
industrial and agricultural systems. Out of it serious consequence relating to salinity, soils
structure and soil permeability can occur.
The most important aim of water reclamation and reuse practices is to reduce the risk
to an acceptable level without having to renounce the wastewater reclamation. The origin of
hazards due to reuse of reclaimed wastewater is (i) biological and (ii) chemical hazard.
Chemicals can generate hazards for humans and ecosystems. They include
compounds originating in urban or industrial wastewaters, added directly to wastewater for
wastewater treatment, or formed during wastewater treatment. Toxic chemicals can be found
in wastewater in concentrations that can lead to acute intoxication, but when these
compounds are in low concentrations, they could cause problems of chronic intoxication as,
for example, in the case of heavy metals or trace organics. The most important measure for
the control of chemical hazard is control of industrial discharges in the urban wastewater
Where reclaimed wastewater is used for applications that have potential human
exposure routes, the major acute health risks are associated with exposure to pathogens
including bacterial pathogens, helminths, protozoa, and enteric viruses. From a public health
and process control perspective, the most critical group of pathogenic organisms are enteric
viruses, due to the possibility of infection from exposure to low doses and lack of routine,
cost-effective methods for detection and quantification of viruses.
Risk acceptability depends on various factors: existing options, cost-benefit
relationships and risk evaluation. Authorities have to assure minimal and acceptable risk.
The health and environmental protection measures need to be tailored to suit the local
balance between affordability and risk.
Costs of additional treatment, distribution and irrigation systems, and monitoring for
effluent reuse can be significant. In any case, a detailed financial analysis is necessary to
ensure stakeholders' awareness of implementation costs. Analysis also has to include the
costs and benefits of any change in environmental values or amenity, and has to be based
on sufficiently long period (life cycle period).
A good decision can be achieved only if costs and benefits of reuse are compared
with the costs and benefits of using alternative water sources. Such comparison has to be
based on integrated analysis of all positive and negative aspects and impacts
(environmental, social and economic). It should take into account any costs needed to
achieve the desired sustainable water quality in the receiving water if the effluent is not
Indirect and environmental reuse options may include reuse via surface and
groundwaters. The most common uses of treated wastewater are for irrigation, industrial
applications, urban applications, groundwater recharge. It includes many options, such as:
- irrigation: pasture, greenhouse crops, non raw-consumed crops, industrial crops, fruit
trees, raw consumed food crops, etc.;
- non-potable urban: toilet flushing, car washing, private garden irrigation, etc.;
- municipal: irrigation of parks, sport fields, street cleaning, fire-fighting, ornamental
- agricultural: food crops and associated food production;
- aquaculture: plant or animal biomass;
- tree growing: irrigation of forest areas, landscape areas and restricted-access areas;
- recreational: impoundments of the water bodies and streams for recreational use in which
public contact with water is permitted (other than bathing) or not permitted;
- environmental; watering, controlling water flow and water bodies characteristics;
- aquifer recharge: by percolation trough the soil or by direct injection;
- industrial: instead of surface water, cooling water, cleaning, fire protection, etc.;
- indirect potable.
The degree of treatment required in individual water treatment and wastewater
reclamation facilities varies according to the specific reuse application and the associated
water quality requirements, Table 7. The simplest treatment system consists of solid/liquid
separation processes and disinfection. Usual treatment system consists of one of secondary
system processes (combination of physical, chemical, and biological processes) employing
multiple-barrier treatment approaches for contaminant removal as well as disinfection.
The reuse system should obtain full approval form authorities, and reclaimed
wastewater must only be reused for the uses for which the permit was issued. Reuse system
must be well managed in accordance with the requirements given directly or indirectly in the
permits. Quality monitoring and process controls should be implemented as a usual and
important part of management. When reclaimed water quality does not meet the fixed
standards, reuse must cease.
Good reuse practice should also have a good response plan for all unusual events
(floods, power disruption, etc.), good protection of public health and environmental quality,
public awareness programme, as well as good preventive maintenance plan.
Effluent management strategies should evaluate reuse options and implement
options that are safe, practical, economic and environmentally beneficial. Surplus effluent
should be managed through one of the discharge options (adequate treatment, safe
More information related to this topic can be found in Regional Guidelines for
Municipal Wastewater Reuse in the Mediterranean Region, UNEP/MAP, 2003.
Land applications have been used to return the discharged water to the water cycle. It
includes systems such as evaporation ponds, soakage systems and irrigation by which water
returns to the water cycle by evaporation and evapotranspiration, or infiltration. In this case
irrigation has a goal to maximise the discharge of water and its return to the water cycle.
This type of discharge of effluent has been traditionally used as an on-site solution for
individual houses where wastewaters, after local on-site treatment, have been discharged on
land by some type of drainage system. Land application for bigger systems is rare but if it is
used than, in most instances, involves the irrigation of land owned by the sewerage
authorities. In this case the principles of effluent reuse have to be applied.
Recommended guidelines for water reuse in the Mediterranean Region
(UNEP/MAP Guidelines for municipal wastewater reuse in the Mediterranean Region)
Intestinal FC or E. Wastewater treatment expected to
nematode(a) coli (b) SS (c) meet the criteria
(No. eggs per (cfu/100 (mg/L)
a) Residential reuse: private garden watering, toilet flushing,
b) Urban reuse: irrigation of areas with free admittance
(greenbelts, parks, golf courses, sport fields), street cleaning, Secondary treatment + filtration +
0.1(h) 200 (d) 10
fire-fighting, fountains, and other recreational places. disinfection
c) Landscape and recreational impoundments: ponds, water
bodies and streams for recreational purposes, where incidental
contact is allowed (except for bathing purposes).
a) Irrigation of vegetables (surface or sprinkler irrigated), green Secondary treatment or equivalent (g)
fodder and pasture for direct grazing, sprinkler-irrigated fruit + filtration + disinfection
b) Landscape impoundments: ponds, water bodies and 1000 (d) Secondary treatment or equivalent (g)
ornamental streams, where public contact with water is not 150 (f) + either storage or well-designed
allowed. series of maturation ponds or
c) Industrial reuse (except for food industry). - infiltration percolation
Irrigation of cereals and oleaginous seeds, fiber, & seed crops,
dry fodder, green fodder without direct grazing, crops for Secondary treatment or equivalent
canning industry, industrial crops, fruit trees (except sprinkler- None 35 + a few days storage
irrigated)(e), plant nurseries, ornamental nurseries, wooden required 150 (f) or
areas, green areas with no access to the public. Oxidation pond systems
Intestinal FC or E. Wastewater treatment expected to
nematode(a) coli (b) SS (c) meet the criteria
(No. eggs per (cfu/100 (mg/L)
a) Irrigation of vegetables (except tuber, roots, etc.) with surface
and subsurface trickle systems (except micro-sprinklers) using
practices (such as plastic mulching, support, etc.) guaranteeing
absence of contact between reclaimed water and edible part of
None Pre treatment as required by the irrigation technology,
b) Irrigation of crops in category III with trickle irrigation systems None required
required but not less than primary sedimentation
(such as drip, bubbler, micro-sprinkler and subsurface).
c) Irrigation with surface trickle irrigation systems of greenbelts
and green areas with no access to the public.
d) Irrigation of parks, golf courses, sport fields with sub-surface
a) Surface spreading into nonpotable aquifers Secondary treatment or equivalent (g)
Secondary treatment or equivalent (g)
b) Surface spreading into potable aquifers - 1000(d) 20
+ filtration + disinfection
Advanced wastewater treatment
c)Direct injection No detectable <5 processes in order to meet drinking
water maximum contaminant levels
Ascaris and Trichuris species and hookworms; the guideline limit is also intended to protect against risks from parasitic protozoa.
FC or E. coli (cfu/100mL): faecal coliforms or Escherichia coli (cfu: colony forming unit/100 mL).
SS: Suspended solids.
Values must be conformed at the 80% of the samples per month, minimum number of samples 5.
In the case of fruit trees, irrigation should stop two weeks before fruit is picked, and no fruit should be picked off the ground. Sprinkler irrigation
should not be used.
such as advanced primary treatment (APT) (Jimenez et al., 1999 and 2001).
As very few investigations, if any, have been carried out on how to reach < 0.1 nematode egg /L, this criterion is considered a medium term
objective and is provisionally replaced by <1 nematode egg /L.
Land application aims to utilise the water and nutrient components in a suitable way
with minimum impacts on:
ecosystem at or near the application site; and
human activities near to site.
Solution/schema for land application depends strongly on the local situation and
characteristics. The most important factors are climate, availability of land, topography,
groundwater, soil properties, and existing and planned land use.
In situations where there is no local surface water, land application is the only way of
effluent discharge to the environment. Water can be returned to the water cycle only via air
(evaporation and/or evapotranspiration) or via groundwater (infiltration).
Land application is one of solutions for protection of very sensitive water bodies, such
as water for drinking purposes, nutrient sensitive waters, karst waters, specially protected
water bodies, etc. It is also one of management options for small communities. Land
application, generally, is very rarely used for large communities.
Discharge to Coastal Waters
For the coastal communities effluent is directly or indirectly discharged to the
associated coastal waters. The aim is to maintain water quality that protects the water body’s
environmental values/water uses. However, for coastal communities the use of the marine
environment for treatment of municipal wastewater is an attractive option and, historically,
the Mediterranean coastal communities have made much use of the treatment and
dispersing properties of the sea for this purpose.
The important part of such concept is sea outfall, which has been designed/used to
ensure that the effluent is discharged in the best practicable environmental manner. The
treatment must be appropriate and the outfall has to be relatively long and equipped with
diffuser to achieve high levels of dilution and dispersion. Usually, a mixing zone around the
discharge point/diffuser will be specified beyond which the environmental uses are
Impact of the effluent on the receiving water body depends on numerous factors, such
quality and quantity of the effluent;
quality of the receiving water body before effluent is mixed;
depth of the sea at the point of discharge, and density profile;
exchange rate of the receiving water body;
hydrodynamics of the water body;
dilution in mixing zone and secondary dispersion out of the mixing zone;
interactions and processes between the effluent and the receiving environment/decay;
sensitivity of the receiving environment.
Most of the Mediterranean population lives in communities located on the coast, and
discharges effluent into the sea, directly or indirectly. It also includes the largest cities. The
general trend in the region is concentration of population in the coastal area/belt and in the
large cities on the coast, which means that this application will be more and more in use.
Wastewater has to be treated before been discharge into the sea. The level of
treatment varies from minimal to secondary treatment with nutrient removal. Level of the
treatment is usually analysed jointly with the outfall arrangements because they are
interlinked and of equal importance for the selection of the appropriate, environmentally safe
wastewater disposal scheme.
The treatment level and the location and design of the outfall depend on many
factors, such as:
the characteristics of the existing wastewater sanitation system;
the environmental values/water uses of coastal sea, estuary or bay;
the total effluent and load flow, and its variation in time (daily and seasonal);
oceanographic and climate aspects;
dilution, dispersion and oxidation and other self-purification characteristics of the
receiving sea body;
community desires and affordability;
regulation and standards.
There is big difference between discharge by coastal outlet and marine outfall. When
discharging treated wastewater into the sea by a coastal outlet then the point of discharge is
on the coast or very near to the coast, and the effluent affects directly all coastal sea uses. In
this case the level of treatment should be much higher, and generally secondary level is
necessary due to absence of dilution and dispersion effects which occur in case when
discharge is via a long outfall. Health risk is very high due to high possibility of direct contact
of humans with mixing waters, and disinfection of effluent is necessary. By using marine
outfall, primary treatment can be adequate in case where receiving water conditions allow it.
It should be pointed out that operation and maintenance costs of the alternative with a
marine outfall and primary treatment are lower that those of the alternative with a coastal
outlet and secondary treatment.
There is a big difference between discharging the effluent into the open sea and bays
or semi-enclosed sea. In the case of effluent discharge into semi-enclosed or closed
ecosystems (such as lagoons), total dilution of waste takes place in a limited quantity of
seawater. As a consequence of limited dilution, waste concentration in waters of semi-
enclosed and enclosed systems may increase and create very negative environmental
impacts (eutrophication). In such cases it is necessary to control nutrient load in the system,
and in that way, tertiary treatment must be prescribed.
In such cases it is necessary to consider also alternative points of discharge outside
the bay or semi-enclosed sea, which generally requires lower levels of treatment. Decision
making on the selection of the method and location of wastewater discharge in areas of
semi-enclosed and enclosed systems relies on environmental capacity/impact assessment
Use of marine disposal of urban wastewater for many coastal communities is very
attractive because it can be safe, effective, and provides considerable cost savings, both
capital and operational. It may be particularly attractive for developing countries owing to the
relatively low levels of treatment, maintenance and energy use compared to alternative
methods. However, environmental values/water uses have to be protected by
implementation of appropriate “combined approach” to water quality management and by
integrated use of treatment and long submarine outfall.
In EU countries, however, this option has been almost totally abandoned, due to the
existing legislation (Directive 271/91), which prescribe rather strict treatment requirements
prior to any effluent discharge into receiving waters.
Discharge to Inland Waters
Inland waters mean all standing or flowing waters on the surface of the land, and all
groundwater on the landward side of the baseline from which the breadth of territorial waters
Where effluent is discharged in inland waters, the aim is to maintain a water quality
that protects the water body’s environmental values (aquatic ecosystems, terrestrial
ecosystems and wetlands directly depending on the aquatic ecosystem, and water uses).
Special attention has to be on groundwater. Surface water and groundwater are in
principle renewable natural resources; in particular, the task of ensuring good status of
groundwater requires early action and stable long-term planning of protective measures,
owing to the natural lag in its formation and renewal. Such time lag for improvement should
be taken into account in timetables when establishing measures for the achievement of good
status of groundwater and reversing any significant and sustained upward trend in the
concentration of any pollutant load.
Factors which influence the impact of effluent on a specific water body, include:
quality and quantity of the effluent;
quality and status of receiving water body;
environmental and hydrological characteristics of the receiving water body;
sensitivity of the receiving environment;
environmental values of the receiving water;
prescribed water uses.
There is big difference between the characteristics of north and south inland waters in
the Mediterranean region. North is much richer with constant-inland waters than south.
Constant surface waters in the south region are rare, and groundwater generally has a long
renewal period, and so inland waters in this region are more sensitive to pollution.
General requirement for discharging effluent into inland waters is at least secondary
level of treatment. For nutrient-sensitive waters, such as standing surface waters, nutrient
removal is necessary. Disinfection is commonly required for surface water discharges, and in
most cases for groundwaters. Especially sensitive are standing surface waters and inland
waters where the effluent is a significant proportion of the total flow. That is a common case
in the arid areas. Karst water resources are also very sensitive due to short retention time in
underground geological formations, fast infiltration and ground water flow (low self-
For the purpose of environmental protection there is a need for a greater integration
of both qualitative and quantitative aspects of surface waters, groundwaters and the
associated coastal sea. The impact of inland water quality on the receiving coastal sea must
Discharges into inland waters, generally, do not take into account the naturally
occurring dilution and self-purification processes, and only partially the mixing zone.
Treatment of wastewater
Wastewater treatment involves various processes used individually or in series to
obtain the required effluent quality. Standard and most important processes are:
preliminary or pre-treatment: removes gross solids, coarse suspended, floating matter,
grease and oils. The main aim of this process is to protect outfall and prevent visual
primary treatment: removes readily settleable solids. It means treatment of urban
wastewater by a physical and/or chemical processes involving settlement of suspended
solids, or other processes in which the BOD5 of the incoming water is reduced by at least
20% before discharge, and the total suspended solids of the incoming wastewater are
reduced by at least 50%. The main aim of this process is to protect outfall operation,
provide minimal environmental protection around point of discharge and prevent visual
and other nuisance;
secondary treatment: removes most of the remaining contaminants, suspended solid,
colloidal and dissolved organic matter. It means treatment of urban wastewater by
processes generally involving biological treatment with a secondary settlements or other
processes in which contaminants in incoming water are reduced to a minimum: BOD5 70
- 90%, chemical oxygen demand 75 %, and total suspended solids 70 - 90 % before
discharge. The main aim of this process is environmental protection from oxygen
depletion and prevention of visual and other nuisance;
nutrient removal: further reduces the content of nitrogen and phosphorus following the
secondary treatment. It means treatment of urban wastewater by processes in which
contaminants in incoming water are reduced to a minimum: total phosphorus 80% and/or
total nitrogen 70 - 80 % before discharging into nutrient-sensitive waters. The main aim of
this process is environmental protection from eutrophication and prevention of visual and
disinfection of effluent: reduces pathogens to levels acceptable for the reuse or discharge
of treated wastewater in most cases into receiving waters. The main aim of this process
is reduction of health risk;
advanced wastewater treatment: further improves the quality of effluent by processes
such as granular media filtration, ion exchange, micro filtration and membrane technology
including membrane bioreactor. The main aim of this process is further improvements of
effluent quality due to enhanced effluent quality requirements (e.g. reuse).
natural treatment systems: imply processes that also take place in the nature in the
“ecosystem reactor”. Physical, chemical and biological processes are applied, as well as
natural environment. This makes them different from mechanical processes where
processes take place in constructed reactors and with introduced energy. The most
frequent processes are: land-treatment systems, slow rate, rapid infiltration and overland
flow; constructed wetlands and aquatic plant treatment systems, and aquaculture
The most common level of treatment is secondary treatment, which usually includes
the first three levels (preliminary, primary and secondary treatment), in series or combined in
varying configurations. Secondary treatment is normally a prerequisite of advanced treatment
and disinfection. Nutrient removal, as well as advanced wastewater treatment, is generally
associated with protection of nutrient-sensitive areas, or specific uses of water bodies such
as drinking purposes. Advanced treatment and disinfection are also associated with effluent
Advance cleaning of wastewater that goes beyond the secondary or biological stage
is also named as tertiary treatment. It removes nutrients such as phosphorus and nitrogen
and most BOD and suspended solids.
Examples of treatment processes:
Treatment level: Examples of treatment process:
A) Pre treatment Screening, grit removal, grease and oils removal
B) Primary treatment Primary sedimentation, Imhoff tank, flotation, micro
C) Secondary treatment Biological treatment (conventional activated sludge,
trickling filter), physical-chemical treatment, lagoons/ponds
D) Nutrient removal Biological treatment, chemical precipitation
E) Disinfection Lagooning, ultraviolet radiation, chlorination
F) Advanced treatment Granular-media filtration, microfiltration, membrane
technology including membrane bioreactor
G) Natural treatment Constructed wetlands, slow-rate systems, overland-flows,
floating aquatic plant, aquaculture
Degrees of treatment achieved by various processes used are presented in Table 8.
Sludge processing and disposal/reuse
Safe handling and disposal of various residual produced in different treatment units is
of equal importance. By-products of wastewater treatment are solids: screenings, grease and
oils, and biosolids or sludge cake. Screenings, grit and send are disposed on landfill or
reused, while grease and oils have to be destroyed, for example, by incinerator.
The sludge (including scum), which may contain solids in concentrations of 0.5 - 5 %,
offers complex processing and disposal problems. It is odours and contains large volume of
water. Because the treatment and disposal of sludge is expensive, sludge-handling costs are
often the overriding consideration in the design of wastewater treatment plants.
In general the sludge-processing and disposal methods include thickening,
stabilisation, conditioning, dewatering, and disposal, Figure 3. Many units operations and
processes are utilised at various stages of sludge processing and disposal. To develop a
cost-effective system of sludge treatment, the best combination of treatment processes must
be chosen. Main factor, which strongly influences characteristics of sludge treatment, is way
of disposal or reuse. Most of the sludge-processing facilities produce two streams: (1)
processed solids and (2) liquids. The liquid streams must be treated again, and these liquids
from various sludge-processing units are returned to the head of the plan.
Sludge arising from wastewater treatment has to be re-used whenever appropriate.
Disposal routes shall minimise the adverse effects on the environment.
Competent authorities have to ensure that disposal of sludge from urban wastewater
treatment plants is subject to general rules or registration or authorisation.
Degree of treatment achieved by various processes used
Treatment processes Removal efficiency, percent
BOD-5 COD Total Suspended Solids Total Nitrogen Total Phosphorus Total Coliforms
A. Pre treatment 0-5 0-5 0 – 10 nil nil 0 - 10
B. Primary treatment 30 - 40 30 - 40 50 – 65 10 - 20 10 - 20 25 - 75
C. Secondary treatment
- activated sludge 80 - 95 80 - 85 80 - 90 10 - 30 10 - 25 80 - 90
- lagooning 90 - 95 85 - 95 60 - 80 20 - 90 10 - 35 90 - 98
- physical-chemical 50 - 70 50 - 70 80 – 90 20 - 30 70 - 90 40 - 80
D. Nutrient removal
- biological nitrogen and 95 - 97 85 - 90 90 – 95 70 - 95 70 - 90 80 - 90
- cholirination of treated - - - - - 98 - 99
F. Advanced treatment
- membrane bioreactor >99 >90 >99 >96 >98 6 log
G. Natural treatment
- constructed wetlands 95 - 98 85 - 90 90 – 95 85 - 90 85 - 90 90 - 98
ABBREVIATION BOD = Biochemical Oxygen Demand
COD = Chemical Oxyben Demand
The treated sludge is used in agriculture, as an urban soil improver for horticultural
purposes, is composted or is used as landfilling or disposed on landfill. The sludge contains
most of the phosphorus and part of nitrogen from the influent wastewater, but also a
proportion of heavy metals, depending on wastewater quality. If a sludge treatment is
supplemented with anaerobic digestion processes than biogas can be produced to be used
for energy production (heating, electricity).
Sludge from treatment
THICKENING 1. Gravity
STABILISATION 1. Chlorine oxidation
2. Lime stabilisation
3. Heat treatment
4. Aerobic digestion
5. Anaerobic digestion
CONDITIONING 1. Chemical
3. Heat treatment
DEWATERING 1. Vacuum filtration
2. Filter press
3. Horizontal belt filter
5. Drying beds
DISPOSAL AND REUSE 1. Land application
- to croplands (reuse)
- to marginal land for land
- to forest land
- to dedicated sites
3. Land filling
Figure 3: Alternative unit operations and processes for sludge processing and disposal
Selection of flow scheme
Many unit operations and processes can be combined to develop a flow scheme to
achieve a desired level of treatment. The level of treatment may range from removal BOD-5
and TSS, nitrogen and phosphorous, to complete demineralisation. To develop the best
possible flow scheme a designer must evaluate many factors that are related to operation
and maintenance, process efficiency under variable flow conditions, and environmental
constraints. Factors that are considered important in selection of flow scheme are:
- land requirements;
- adverse climatic conditions;
- ability to handle flow variations;
- ability to handle influent quality variation;
- industrial pollutants affecting processes;
- reliability of the processes;
- ease of operation and maintenance;
- occupational hazards;
- air pollution;
- waste product.
A targeted waste management strategy must set priorities and goes well beyond a
selection of conventional technologies. Many developing countries simply adopt the effluent
standards or regulatory water quality objectives from developed countries. These prove too
ambitious, which does not allow for gradual implementation of a realistic mitigation
programme. The priority wastewater constituents must be identified and cost-effective
mitigation approach selected. Generally, removing the first 50% of the pollutant load is
moderately expensive, but removing the next 40% is more expensive, and removal of the last
10% is often prohibitively expensive.
Box 4: Basic design consideration for wastewater treatment facilities
Basic designing factors are:
1. Initial and design years
2. Service area
3. Site selection
4. Design population
5. Regulatory control and effluent limitations
6. Characteristics of wastewater
7. Degree of treatment
8. Selection of treatment processes
9. Equipment selection
10. Plant layout and hydraulic profile
11. Energy and resource requirements
12. Plant economics
13. Environmental impact assessment
The aim of sea outfall management is to ensure that the wastewater is discharged in
the best practicable environmental manner. Wastewater treatment plant and submarine
outfall must be considered as an integral part of the wastewater system, both in engineering
and an environmental sense.
Coastal waters, naturally, have low biological oxygen demand (BOD) and are
saturated, or supersaturated, with dissolved oxygen (DO). Significant increase in BOD and
decrease in DO rarely occur, except in case of significant effluent discharges into estuaries
and enclosed bays. The concentration of other variables depends on local influences such as
climate, geology and hydrological characteristics/fresh water influence.
The sea characteristics have a strong impact on bacteria life cycle resulting in their
quick and high reduction in the sea due to mortality and dilution. Many mechanisms
contribute to the mortality of enteric micro-organisms in the sea, but two are the most
important starvation and radiation.
Generally, nutrient level in the sea is too low to support the growth of enteric bacteria.
Exceptions are confined waters and the vicinity of an outfall where nutrient concentration can
be high. During daylight, lethal solar radiation greatly accelerates the bacterial die-off. The
ultraviolet light is the most lethal.
The rate of bacterial mortality is expressed in terms of the time taken for 90% of the
bacteria to die-of, the T90 value. The value of T90 = 2,5 hours for faecal coliforms, 3,5 hours
for faecal streptoccocci and 3,0 hours for total coliforms are the most common applied in
estimating bacterial decay in seawater.
These characteristics of seawater provide the basis for the use of the marine
environment for additional treatment of urban wastewater in which submarine outfall
arrangements have a very important role.
Submarine outfall equipped with diffuser provides quick and high dilution of effluent in
marine environment reducing concentration of all wastewater substances to the level, which
does not negatively influence the marine environment outside the mixing zone. The negative
impact on the sea environment is smaller if dilution is higher and if point of discharge is more
distant from the coast and protected areas.
However, environmental conditions of the receiving sea, especially sensitivity to
eutrophication, as well as environmental values/water uses have a strong influence on the
level of the treatment of urban wastewater prior to discharging by submarine outfall. Nutrient-
sensitive areas, as well as use of the sea body for aquaculture and recreation purposes will
require a high level of treatment.
The use of a long submarine outfall with lower level of wastewater treatment is
acceptable in cases of smaller communities, less than 10.000 e.p., and as a first phase of
wastewater sanitation system development (in case when wastewater collecting network is
incomplete) insuring appropriate protection of environmental values.
The minimum acceptable level of treatment in many cases is primary treatment
providing that effluent is discharged into marine environment via a long submarine outfall.
The length of the outfall from coastline should be at least 1000 m, and depth of water
at the point of discharge 20 m if it is to be considering a long submarine outfall. Both criteria
have to be respected. In case of small communities (smaller than or equal to 2000 p.e.) the
outfall can be shorter but not less than 500 m. In all cases, length of the outfall at the point of
discharge has to be determined by considering the prevailing water conditions
In any case, effluent should not have negative impacts on environmental values of
the receiving water body, which has to be confirmed with appropriate prediction model and
environmental impact assessment study.
The long submarine outfall is the most practical method for the discharge of effluent
into the sea because it highly reduces the risk to the environmental values of the receiving
water in case of inappropriate functioning of the treatment plant and incidental situations
(malfunctioning). Thus, the long submarine outfall is a very practical solution for the areas
(wastewater sanitation systems) lacking skilled manpower for the running of the treatment
Box 5: Main elements and steps of submarine planning and design
Main elements and steps of submarine planning and design are:
- Assessment of sewerage catchment and wastewater flow (estimation of pollution load
- Site survey information (assessment of mixing characteristics of sea and sea bed
- Use Area definition including mixing zone characteristics;
- Environmental standards determination associated with Use Area;
- Marine treatment schemes analysis and selection (wastewater collection network, pump
- Definition of land- based treatment schemes (determination of treatment plant
- Selection of headworks and outfall site (selection of the optimal locations in accordance
with local conditions/requirements and wastewater collection system characteristics);
- Headworks and storm overflow arrangements (integral analysis and selection of the
- Environmental design (degree of treatment, the storm overflow settings, the discharge
rate, the discharge location, the degree of initial dilution);
- Outfall and diffusers arrangements (minimisation of cost of providing environmental
- Hydraulic design (selection of size of outfall, velocity of flow and velocity of discharge at
diffuser orifice) ;
- Environmental impact prediction (considering the most critical situation related to
environmental values/water uses);
- Elimination of environmentally unacceptable schemes;
- Civil engineering design (marine structural design);
- Selection of economic options (construction, operation and maintenance costs, and
comparison with other disposal alternatives).
One of the important elements of submarine outfall utilisation is the definition of the
“mixing zone” and relevant environmental standards. Mixing zones are adjacent to point
sources of effluent. The “mixing zone” covers the initial dilution zone and the zone of rapid
secondary dilution following the discharge. In mixing zone the Environmental Quality
Standard values for other Uses may be exceeded except for the aesthetic standard. In a
management context, mixing zones are often defined as exclusion zones.
The boundary of mixing zone is usually defined in terms of the concentrations of
indicator species in the effluent. Its extent and nature depend on hydrological/oceanographic
conditions at the outfall site, discharge volume, currents, depth, tides, wave actions, dilution,
way of discharge, etc. In case of high and quick dilution, the zone can be small, while in case
of low-energy systems, such as closed sea areas and bays with small discharge, mixing may
be slower and the mixing zone will be larger.
The management objective in the allocation and monitoring of mixing zones should
be to minimise the potential for ecological detriment, especially permanent degradation. A
mixing zone can not be allocated in the areas where strict environmental values/water uses
apply including human consumption, and areas of extremely high environmental significance.
Depending on the local conditions, the following restrictions may be applied to
achieve best practice in mixing zone management:
- Adequate treatment prior to effluent discharge - minimum aesthetic standards;
- Discharge under specific hydrological conditions (tide water);
- The area extent of the mixing zone should be restricted;
- A requirement may be made for the effluent release to be pulsed (periodical discharge);
- Minimal initial dilution rate can be required to satisfy standards for some indicator
- Type of diffuser can be prescribed;
- Minimal depth of the sea and minimal distance from the coast for the point of discharge
can be prescribed;
- Extreme conditions for selection of solution may be required and prescribed;
- Specific monitoring programme.
Generally, the acceptable distance of the boundary of a mixing zone from the
discharge point is at least 300 m. Mixing zone can never be extended to the coastline.
The following has to be stressed: (i) the benthic environment/organisms in the mixing
zone are under stronger stress and can be completely destroyed near the discharge point;
(ii) the extent of the mixing zone can be unpredictable where oceanographic/hydrological
conditions are variable; (iii) subtle ecological detriment may be caused at sites remote from
the mixing zone.
Treatment and disposal design philosophy
One of the challenges of sustainable development is to find ways of enhancing our
total wealth while using common natural resources prudently. Renewable resources, such as
water, should be used in a ways that do not endanger the resources or cause serious
damages or pollution.
Reversing or rectifying damage to the environment can be difficult and costly. For this
reason pollution should be prevented from taking place, rather than cleared up after it has
happened. And, wherever possible, the need to respect the environment should be reflected
in other policies.
Different environmental conditions that exist in different places need to be taken into
account in reaching decisions on water treatment and disposal. Decision on treatment and
disposal has to be based on objectives set by the authorities for the quality of the stretch of
water to which he discharge is made as well as any relevant standards from national or
The aim of wastewater treatment and outfall/disposal design is to ensure that the
wastewater is discharged in the best practicable environmental manner. The environmental
safeguards have considerable effects on the capital and operating costs of the outfall and
treatment plant. The costs are also strongly influenced by the interaction between the
outfall/disposal system, treatment plant and wastewater collecting system.
Environmental quality objectives
An Environmental Quality Objective EQO is the requirement that a body of water
should be suitable for those uses identified by controlling authorities. The uses are protected
by one or more Environmental Quality Standards EQSs. An EQS is a specified concentration
of a substance, which must not be exceeded if a given use is to be maintained. The idea of
controlling the quantity of a substance discharged to a body of water, so that its
concentration does not exceed the value above which undesirable effects are expected,
goes back many years.
The concept may be applied by defining the areas for which particular Use area
desired. Applying the appropriate standard protects each Use. Where more than one EQS
relates the most stringer will apply. The EQSs for each Use Area comprise those directly
required to achieve the Objectives and those, which are required to protect the Use.
The drawing up of the Use Area boundary is a multidisciplinary activity involving
development and land use planners, biologist, chemists, environmentalists, the general
public, politicians and other interest parties, as well as engineers designers of treatment plant
and outfalls. Definition of the Use Areas provides the engineer with a set of standards to
which he can design.
Consultation with the appropriate authorities should be commenced at the inception
stage, to ensure that the eventual design will satisfy the consent criteria. Public consultation
is generally a necessary step in the construction of a treatment plant and outfall.
Consideration should be given to seasonal variations in the Use Areas due to
changing bathing habitats, the passage of migration fish and other seasonal changes. These
variations in Use may be taken into account in design.
Design of wastewater sanitation schemes/sewerage schemes
On a wastewater scheme the engineer’s role is generally to provide the engineering
design and costs for the assessment and selection of the appropriate environmentally safe
wastewater disposal scheme. The engineer is constrained to work very closely with
environmental scientists during all stage of the design to ensure that the designs will be
The engineering design provides the basis for the comparison and selection of the
preferred scheme each stage of the design process. Good engineering design is required
ensure that the financial cost of meeting the Environmental Quality Standards requirements,
and hence protecting the environment, is kept to a minimum. There are a number of factors
within the control of designer, which should be considered in developing a design:
- Characteristics of wastewater collection system (catchment area and wastewater flow);
- Use Areas characteristics and environmental requirements/constrains (Environmental
- Site survey data of recipient and possible treatment plant and outfall/effluent discharge
- Selection of treatment plant and outfall/effluent discharge site;
- Selection of sludge disposal site or reuse alternatives;
- Treatment plant design;
- Outfall and diffuser design;
- Hydraulic design;
- Marine and structural design;
- Environmental impact assessment;
- Risk assessment;
- Cost assessment.
Wastewater catchment Use Areas Sites survey data
and wastewater flow
Marine treatment Inland treatment schemes
Treatment plant and Environmental design Treatment plant sites
outfall sites and effluent discharge sites
Sludge disposal/reuse sites Sludge disposal/reuse sites
Selection of treatment plant Selection of treatment plant
liquid flow schemes liquid flow schemes
and sludge flow schemes and sludge flow schemes
Outfall and diffuser Effluent discharge
arrangements and/or reuse arrangement
Hydraulic design Hydraulic design
Sludge disposal Environmental impact Sludge disposal
and/or reuse prediction and/or reuse
Selection of the optima
Civil Engineering Design
Select economic options
Figure 4: Wastewater sanitation schemes - design flowchart
Possible approach to engineering design is illustrated in Figure 4. The central role of
the environmental activities in the design processes shows the importance of close co-
operation between the engineer and scientist. It is especially important related to elements of
the design process: environmental design and environmental impact assessment.
During the feasibility, outline and detailed design stages the engineering design is
considered in progressively increasing detail. At the feasibility stage all the options are
considered, usually as desk studies, on the basis of he existing information. A limited
preliminary field investigation may well assist in the early elimination of unsuitable shemes.
The unsatisfactory schemes are eliminated and the feasible schemes costed and the
likely environmental impact assessed to provide the executive decision makers with
adequate facts to decide which designs should be considered at the outline design.
The outline design stage will vary from optimisation of one preferred scheme to the
comparative assessment of several possible schemes. Some fieldwork is essential at this
stage particularly to evaluate the mixing characteristics of receiving waters as well as
environmental impacts. The aim of outline design is to present the executive decision-makers
with the cost and financial basis for the selection of the final scheme.
The detailed design stage commences once the preferred outline design has been
selected. Accurate field data is required for detailed design. The designer must be prepared
to revise and update the preferred scheme in the light of the new data collected for detailed
At the end monitoring system have to be designed and set of appropriate indicators
have to be proposed for verifying the degree of accomplishment of the expected results, as
well as efficiency and effectiveness of the system. Monitoring system has to be harmonised
with requirements set by appropriate authorities as well as characteristics of the wastewater
sanitation system. Monitoring is associated to a continuous improvement process, which has
to be kept continued through evaluating the results and, updating the treatment processes
according to the scientific progress and changes in the socio-economic framework.
5. GUIDELINES FOR DISPOSAL
Guidelines for Land Application
Land application is the discharge of the effluent on an area of land with the primary
aim of returning the water to the water cycle by evaporation, evapotranspiration and/or
infiltration. This is one of measures that are part of sustainable water resources management
or water conservation. These guidelines describe the levels of treatment required for effluent
prior to land application, Table 9.
The land application does not include raw water discharge because it is not part of
Water quality limits are set to minimise potential health risk and negative effects on
the receiving environment. The prescribed limits should be monitored to determine
The basic principles for land application are:
- secure long-term sustainable land use avoiding build up of any substances in the soil;
- the effluent is not detrimental to the vegetation cover;
- avoid any change of the soil structure;
- any runoff to surface waters and/or percolation to groundwater should not compromise
the selected environmental values of the receiving waters;
- no gaseous emissions to cause nuisance odour;
- no aerosol formation to cause health and other problems in neighbouring areas;
- implement insect control measures to reduce mosquitoes nuisance;
Land application is a feasible alternative for inland communities, especially smaller
communities in arid and semiarid areas for total effluent disposal or surplus effluent disposal
after application of reuse.
This method is also feasible in areas where direct discharge to the surface and
ground water is not permitted, such as water for drinking purposes or very sensitive waters.
Application and loading rate have to be carefully planned, managed and monitored so that
any discharge in groundwater and surface waters will comply with the required quality of
receiving waters and environmental values/water uses. Infiltration from land application
results in aquifer recharge. In any case, it is more suitable if effluent reaches water resources
by infiltration than runoff, providing that infiltration will result in additional treatment of
effluent. Land application can be used as a method for artificial recharge of aquifer using
appropriate levels of treatment.
In any case, it is recommended that this method use a storage capacity before land
application. The storage can be used for storage of effluent for the period when rate of
discharge by land application is reduced due to climate or any other reasons (maintenance,
system backup, and reliability). In addition, storage provides additional treatment of effluent
especially related to bacteriological quality of effluent. Longer detention period produces
better quality of effluent. But, longer detention period requires bigger storage and so
produces higher costs. The cost of providing the storage can be significant, and depends on
This method of effluent management varies and strongly depends on the local
conditions. The biggest concerns are toxicants and the possibility of build up of their
concentrations in the soil and vegetation. Anther concern is the impact on waters and aquatic
environment. That way planning of this application requires close co-operation of different
experts and authorities. With appropriate management of treatment processes and hydraulic
system good and safe application can be achieved.
Table 9 lists discharge options, guideline treatment levels, the limiting factors for each
land application option, and associated parameters likely to be of concern.
The most important element is minimal level of treatment. The level must be practical
and safe for the particular discharge option. In setting the level of treatment, the local
community has to be consulted. The type of land application, local conditions and public
interest will determine the level of treatment required.
The limiting factors should be considered adequately and analysed in detail before
adopting a particular option. Appropriate assessment of the local social, economic and
environmental conditions is prerequisite of a good setting of solution. Analysis of alternative
options has to be based, among others, on appropriate environmental impact assessment
Guidelines for Coastal Waters
Coastal marine waters serve a wide variety of exceptionally important human uses.
Many of these uses produce high local benefits, such as yield of fish, shellfish and
recreational activities/tourism. Others involve regional benefits or global unity of the marine
system, since local events influence, and are influenced by, water quality at distant point.
Many of human uses of marine waters are directly dependent upon the nature and quality of
the biological, chemical, and physical systems present. That way the maintenance of
acceptable water quality is a priority.
The effluent is discharged into different coastal waters: open coastal waters,
estuaries and bays.
The effluent can be discharged directly into the sea by long/extended submarine
outfalls far from shore, or nearshore/coastal discharge sites or coastal outlets. The effluent
can also be discharged into sea indirectly, via discharges into rivers, estuaries and
Wastewaters are collected and transferred to a treatment plant and, following an
appropriate level of treatment, discharged into the sea through an outfall. The outfall consists
of a pipeline, whose purpose is to convey the effluent, some distance offshore, terminating in
a diffuser. Clearly, the ultimate impact of the discharge depends on the level of the treatment
and the outfall design; the whole disposal process should be thought of as a system
comprising the marine outfall and treatment plant.
For a long time marine waters have been used for discharge of effluent because
dilution was a practical solution for the pollution. Dilution, dispersion and self-purification of
sea water are valuable processes for reduction of non-toxic and non-accumulative pollutants
providing that recipient is large enough to accommodate waste without unacceptable effects.
General rule is higher rate of dilution less, negative impact on environment, considering that
there are no cumulative build-ups of negative processes.
Land discharge options and treatment levels
LAND APPLICATION LIMITING FACTORS FOR EFFLUENT PARAMETERS MINIMUM LEVEL COMMONLY
DIFFERENT SEGMENTS OF MAJOR CONCERN OF TREATMENT REQUIRED LEVEL
OPTIONS OF THE ENVIRONMENT OF TREATMENT
Evaporation ponds Air - aesthetic enjoyment (odours), Odour emission, aerosols,
mosquitoes and other insects. toxicants, Nil C
Water - seepage, run-off. organics (BOD-5),
Evapotranspiration Air - odours. Odours, dissolved solids,
(irrigation) Land - potential for long-term soil aerosols, toxicants, pH, B C and E
(i) agricultural contamination and adverse pathogens, nutrients. (only if special safe C and E
impacts on vegetation and soil technique of irrigation
(ii) landscape structure. is applied)
Infiltration Groundwater - existing and potential Solids, BOD-5, nutrients, C and D
- natural environmental values. Aquifer clogging. pathogens, toxicants, C
- ground artificially Land - potential for long-term dissolved solids, pH.
conditioned degradation of land and/or crops and
- aquifer recharge vegetation.
NOTES: PLANT TYPE - TYPICAL TREATMENT PROCESSES
Treatment Process Category Parameters to be removed Examples of Treatment Processes
A Pre Treatment Gross solids , grease and oil Screening, grit and grease chamber
B Primary Treatment Gross solids plus readily settleable solids Primary sedimentation, flotation
C Secondary Treatment Most solids and BOD Biological treatment, physical-chemical treat., Lagoons
D Nutrient removal Nutrients Biological treatment, chemical precipitation.
E Disinfection Bacteria and viruses Lagooning, ultraviolet radiation, chlorination.
Long outfall/extended outfall characteristics depend predominantly on buoyancy
generated turbulence to achieve initial dilution. It is the rising phase as the buoyant
wastewater travels from its discharge point near the seabed towards the surface. During this
short period (several minutes) concentration of effluent and contaminants may be rapidly
reduced. The initial dilution is usually achieved by means of a diffuser, which is a manifold
system that releases the flow through a series of adequately spaced small ports.
After initial dilution, the subsequent secondary dilution or dispersion occurs. This
process contributes further to the distribution of wastewater in the marine environment and
occurs due to advection, turbulent dispersion, wind induced drift and water exchange in the
vertical direction. Advection determines the movements of the wastewater field. Turbulent
dispersion spreads the wastewater field due to shears induced by current velocity differences
and large scale turbulent addies in the receiving medium. Wind-induced drift of the surface
water results from the occurrence of sea breeze. Thus the bacteria and viruses may be
transported towards the coastline or other protected areas in the surface layer of water, due
to direct wind shear and mass transfer due to wave crest breaking. Especially landward-
directed wind may be of particular importance for the bathing water quality at the beaches.
The secondary dilution is usually achieved by appropriate length of outfall from the coast
(distance form protected areas). In the case of persistent pollutant total dilution is the results
of initial and secondary dilution exclusively.
Predators and the antagonistic effects of oxygen, salt water and ultraviolet radiation in
marine environment contribute to reduction and ultimate destruction of bacteria and
pathogens. For them and other non-persistent pollutants the low of decay as a function of
time forms the basis for the calculation of an ambient factor equivalent to dilution named
“tertiary dilution”. Longer contact time period (it generally means outfall) of non-persistent
pollutant with sea, results in a higher rate of decay.
Total dilution is the product of three partial dilutions. The contribution of each phase
to overall dilution is highly dependent on the local conditions. A long/extended outfall will
normally have an initial dilution of 100:1 or better in near field. This is the equivalent, in
terms, of contaminant concentrations, of 99 % removal in the treatment plant. This is much
more than conventional treatment plant process can attain.
In case that effluent is discharged near coast or by coastal outlet, the level of dilution
is very small or insignificant, and in such cases the principle of self-purification of waste in
the sea can not be considered. In such cases, the mixing zone is very restricted or absent.
Accordingly, in this situation the level of the treatment is higher, and the minimum required
level is secondary.
Use of sea for additional treatment of effluent discharged via long submarine outfall
and diffuser system is still today an attractive and realistic option for some countries in the
region. Such alternative can be used if environmental capacity is sufficient to accommodate
the remaining waste after a partial treatment, and if it is the initial step in the development of
higher level of treatment/protection of sea. The important element of such approach is
monitoring, which has to provide sufficient information on the impact on water quality,
sediment and biological community. Monitoring has to be in place before discharge starts so
that baseline information can be collected.
Treatment plant and submarine outfall have to be considered integrally, as a unique
treatment scheme. Long/extended submarine outfall has to be used in all cases when
disinfection is not used in treatment scheme. Disinfection can not be used if effluent has not
been treated with at least secondary level of treatment. So, long/extended submarine outfall
has to be used in all cases when secondary level of treatment is not applied.
It is recommended that long/extended submarine outfall is also used in cases when
secondary or higher levels of treatment have been applied, in order to increase reliability of
wastewater treatment system and protection of environment, and as back-up system for
incidental or malfunctioning situations.
Table 10 lists the various categories of discharge to coastal waters, and indicates the
related environmental values, issues and guideline treatment levels that apply. These
categories are dependent upon the mixing processes that dominate the discharge.
By using a long submarine outfall, the level of treatment, in principle, can be lowered.
For communities whose treatment schemes include long submarine outfall, the following
- less than 10,000 population equivalent, minimum level of treatment is pre treatment;
- less than 10,000 population equivalent discharging water into nutrient-sensitive areas,
minimum level of treatment is primary treatment
- between 10,000 and 150,000 population equivalent, minimum level of treatment is
primary treatment, providing that effluent is not discharged into nutrient-sensitive waters;
- with population equivalent bigger than 150,000, minimum level of treatment is secondary,
providing that effluent is not discharged into nutrient-sensitive waters;
Estuaries, bays and semi-enclosed coastal sea can be considered as sensitive areas
because of small rate of water exchange in these areas, and because they are generally
shallow and there is little buoyancy mixing. In addition, because of the proximity of the
shoreline, there is little opportunity for subsequent dispersion/secondary dilution. In such
cases, a satisfactory discharge is dependent upon the velocity of the discharge, tidal mixing
and higher levels of treatment. Nitrate is usually the limiting nutrient for coastal waters, and in
such cases appropriate reduction of nitrate may be required.
When considering the problem of discharge of effluent into marine environment it is
necessary to adequately consider the specific characteristics of the wastewater flow and load
in tourist municipalities where high seasonal fluctuation exists due to high population/tourist
fluctuation. This fluctuation can be very significant, at a rate of 1:10 and more, and can limit
the application of certain treatment techniques sensitive to fluctuation of flow and loads.
Simpler and more robust treatment solutions with a long submarine outfall were found to be
suitable and reliable discharge scheme. In such cases, discharge systems work with full
capacity 3 to 6 months, and the rest of the year with significantly smaller loads. Accordingly,
in such situations, less restrictive standards may be applied considering that total yearly load
will not endanger the environment. Long submarine outfall is prerequisite in such situations in
order to provide necessary health and safety levels to tourist and marine water users.
The most important element is minimal level of treatment. The level must be practical
and safe for the particular discharge options. In setting the level of treatment the local
community has to be consulted. The type of marine application, local conditions and public
interest will determine the level of treatment required.
The limiting factors should be considered adequately, and analysed in detail before
adopting a particular option. Appropriate assessment of local social, economic and
environmental conditions is prerequisite of good setting of solution. Analysis of alternative
options has to be based, among others, on appropriate environmental impact assessment
study. The common required level of treatment is the level most likely to be used and
It is always useful to analyse more alternative solutions for effluent discharge into the
sea considering different levels of treatment and associated length of outfall taking into
account the existing and long-term needs. In selection of the optimum alternative, based on
prepared criteria, multicriterial analysis is usually applied. Selection criteria are generally
- ecological parameters (impact on the ecosystem);
- economic effects (direct and indirect costs);
- administrative aspects (standards, influence on the existing waste management and
- political aspects (interrelations on local and national levels);
- time aspects (time of completion and recurring impact on environment).
Time aspect is very important in the development of a sustainable solution. The
solution has to be sustainable under today’s conditions and under expected future condition.
Marine outfall and gradual development of treatment plant with successive increase of
treatment level is generally very suitable wastewater management alternative for a
Guidelines for Inland Waters
In many areas of the Mediterranean region, wastewater infrastructure does not meet
the demands created by an increasing population and development, especially in coastal
areas. Many Mediterranean countries, especially in the southern and eastern parts, are
undergoing rapid and/or economic growth and urbanisation resulting in improper wastewater
management. They experience increasing levels of water pollution with accumulative impacts
on human health. Shortcomings in sanitation and wastewater management will remain the
principle factor of resource degradation through water quality degradation.
These issues highlight the need for wastewater sanitation systems to manage the
impact of urbanisation on land waters and the need for increasingly more stringent controls
of effluent. The goal is to manage wastewater sanitation systems in such a way as to meet
present and future needs by developing lower-cost but adequate services that can be
implemented and sustained at the community level. It can be realised by identification and
implementation of strategies and actions that will reverse current trends of resource
degradation and depletion.
Waste management principles are crucial in managing effluent discharge to inland
Issues to be considered in discharging effluent to inland waters include:
avoiding or reducing the amount of contaminants in the effluent through appropriate trade
waste controls and customer education;
reusing or recycling treated effluent where practical;
returning effluent to a stream to provide environmental flows only where effluent quality is
at least commensurate with ambient water quality objectives;
adopting accepted modern treatment technology with the aim of improvement over time;
adapting, where necessary, appropriate treatment technologies to the local working
skill/experience with the aim of gradual and sustained improvement in time;
adapting, where necessary, appropriate treatment technologies and levels of treatment to
the local population's financial capacities with the aim of gradual and sustained
improvement in time;
applying environmental quality guidelines for effluent where the discharge is a major
determinant of the receiving stream quality;
avoiding discharges entering potable water supply off-takes and stretches of streams
having environmental value by optimal location of the discharge pipes.
Coastal waters discharge options and treatment levels
DISCHARGE OPTIONS LIMITING ENVIRONMENTAL EFFLUENT PARAMETERS MINIMUM LEVEL COMMONLY
VALUES/SEA USES APPLYING OF MAJOR CONCERN OF TREATMENT REQUIRED LEVEL
TO EACH DISCHARGE OPTION OF TREATMENT
coastal waters Maintenance of aquatic ecosystems. Toxicants, pathogens, A A < 10.000 p.e.
via long/extended outfall floatables, oil and grease, 10.000 < B < 150.000
suspended solids. C > 150.000 p.e.
* tourist community with * peak load in
high seasonal wastewater season:
flow fluctuation (minimum A A < 50.000 p.e.
ratio: winter/summer = 1/ 5) 50.000 < B < 150.000
C > 150.000 p.e.
coastal waters Maintenance of aquatic ecosystems, Pathogens, toxicants, B < 10.000 p.e.
nearshore or coastal outlets
recreation - primary contact, floatables, oil and grease, colour, C
(other than bays and aesthetic enjoyment. suspended solids, nutrient C for others
estuaries) impact, surfactants.
bays, estuaries, Maintenance of aquatic ecosystems, Oil and grease, nutrients,
semi- C < 10.000 p.e. C and D
recreation - primary & secondary pathogens,
enclosed sea or enclosed toxicants,
sea contact, aesthetic enjoyment. floatables, colour, suspended
solids, BOD-5, surfactants.
NOTES: PLANT TYPE - TYPICAL TREATMENT PROCESSES
Treatment Process Category Parameters to be removed Examples of Treatment Processes
A Pre Treatment Gross solids, grit, grease and oils Screening, grit and grease chamber
B Primary Treatment Gross solids plus readily settleable solid Primary sedimentation, flotation
C Secondary Treatment Most solids and BOD Biological treatment, physical -chemical treatment, lagoons
D Nutrient removal Nutrients
E Disinfection Biological treatment, chemical precipitation.
Bacteria and viruses Lagooning, ulltraviolet radiation, chlorination.
If necessary, due to financial, social and other constrains that effluent causes water
quality objectives to be exceeded, the mixing zone associated with the discharge should be
defined and designated in a waste discharge licence. The aim must be to progressively
reduce the declared mixing zone size until the discharge no longer impairs water quality
objectives. The impact of effluent on waters, including the mixing zones, should be
monitored. Appropriate control measures of use and access to mixing zone have to be
implemented in order to reduce health hazards.
When considering appropriate measures it is necessary to understand that the
restoration of a system to its former state is usually far more costly than prevention.
The most important element is minimal level of treatment. The level must be practical
and safe for the particular discharge options and environmental values. In setting the level of
treatment the local community has to be consulted. The type of application will depend on
the local conditions, public interest, and affordability.
The limiting factors should be considered adequately and analysed in detail before
adopting a particular option. Appropriate assessment of the local social, economic and
environmental conditions is prerequisite of good setting of solution. Analysis of alternative
options has to be based, among others, on appropriate environmental impact assessment
study. The common required level of treatment is the level most likely to be used and
approved. Generally, for inland waters, the secondary level of treatment is necessary in order
to protect human health and the environment. It is especially necessary for the countries
lacking the water for irrigation because there is high possibility that effluent will be reused
,controlled or uncontrolled.
Table 11 sets out the effluent parameters of concern and the guideline treatment
levels for discharge to inland waters.
Inland waters discharge options & treatment levels (Inland waters related with Mediterranean basin)
INLAND WATER LIMITING ENVIRONMENTAL EFFLUENT PARAMETERS OF MAJOR MINIMUM LEVEL COMMONLY
OPTIONS VALUES/WATER USES CONCERN OF TREATMENT REQUIRED LEVEL OF
APPLYING TO RECEIVING TREATMENT
rivers, streams and ecosystem protection dissolved solids, toxicants, floatables, C C and D
lakes colour, turbidity, TSS, nutrients, BOD-5,
recreation and aesthetics toxicants, floatables, colour, turbidity, C C and D
TSS, nutrients, BOD-5, COD, pathogens, (E for primary contact)
odour, oil and grease.
raw water for drinking water dissolved solids, toxicants, floatables, C C, D and E
supply colour, turbidity, TSS including algae,
nutrients, BOD-5, COD, pH, pathogens, C and D*
taste & odour producing compounds.
agricultural water dissolved solids, toxicants, floatables, TSS, C C
BOD-5, COD, Total N, pH, pathogens. C and E*
industrial water dissolved solids, toxicants, floatables, C C
colour, turbidity, TSS, nutrients, BOD-5, C and E*
NOTES: PLANT TYPE - TYPICAL TREATMENT PROCESSES * in sensitive areas as dry rivers; other constrains also have to be
considered (flow, distance from point of discharge, etc.)
Treatment Process Category Parameters to be removed Examples of Treatment Processes
A Pre Treatment Gross solids, grit, grease and oils Screening, grit and grease chamber
B Primary Treatment Gross solids plus readily settleable solid Primary sedimentation, flotation
C Secondary Treatment Most solids and BOD Biological treatment, physical-chemical treatment, lagoons
D Nutrient removal Nutrients Biological treatment, chemical precipitation
E Disinfection Bacteria and viruses Lagooning, ultraviolet radiation, chlorination
6. SAMPLING AND MONITORING
Monitoring is an essential part of the implementation of the whole range of water
legislation. EU countries have to ensure establishment for monitoring of water status in order
to establish a coherent and comprehensive overview of water status within each river basin.
In 1975, Mediterranean countries established the monitoring programme “MED POL” in
accordance with the requirements of the Barcelona Convention (Article 1), and they Article 3
of the Land-based Source Protocol (LBS). The programme includes monitoring of coastal
waters and sources of pollution.
Sampling and monitoring of the environmental and effluent are needed to determine
- the predicted effluent quality is achieved;
- the level of impact or change caused by the management system is as predicted;
- the agreed environmental values are met:
A sampling programme for the environment is usually based on the output from a
detailed site study and consideration of the discharge’s nature and volume. However,
relevant regulations require a certain sampling programme to be implemented and
information to be delivered. The EU Water Framework Directive describes in great detail a
monitoring programme that has to be implemented, including:
1. Surveillance monitoring for:
- supplementing and validation of the impact assessment procedure;
- an efficient and effective design of the future monitoring programme;
- the assessment of long-term changes in natural conditions;
- the assessment of long-term changes due to widespread anthropogenic activity.
2. Operational monitoring undertaken in order to:
- establish the status of those water bodies identified as being at risk of failing to
meet their environmental objectives, and
- assess any changes in the status of such bodies resulting from the programmes of
3. Investigative monitoring carried out:
- where the reasons for any exceedances are known;
- where surveillance monitoring indicates that the objectives set for a body of water
are not likely to be achieved;
- to ascertain the magnitude and impact of accidental pollution.
Each country has its own monitoring programme in accordance with the national
regulations and international obligations. A broad range of aspects needs to be considered
when assessing the impact on the environment, such as:
A) For water:
- the current background quality of the water body;
- status of ecosystems, both pre and post discharge;
- modelling of effects on the receiving environment, including the effects from all other
discharges to the water;
- sampling the water in and beyond the mixing zone, and sampling of sediments and
- establishing control sites beyond the influence of the discharge to identify changes
unrelated to it;
- biological monitoring e.g. macro invertebrates;
- evaluating the biological impact of the discharge.
B) For land:
- soil type;
- vegetation cover;
- potential for runoff;
- proximity to streams and lakes;
- evaluating the impact of the discharge;
- sampling of groundwater, nearby surface waters, soil and crops.
C) For products based on wastewater and sludge reuse:
- reused effluent/sludge application;
- vegetation production and use;
- mobility of pollutants from land sources;
- prioritise sources and causes;
- possible impacts on environment and consumers of food produced by reuse;
- amount of toxic, persistent or bio-accumulable materials in effluent, sludge and products;
- health effects and risks.
Monitoring of environmental changes related to effluent discharges is complex and
expensive. The frequency and scope of monitoring need to be considered on a case-by-case
basis, and have to be implemented in accordance with relevant national and international
standards (ISO, EN, etc.), and requirements. This problem is well documented and regulated
by EU directives and norms.
Competent authorities or appropriate bodies shall monitor:
- discharges from urban wastewater treatment plants to verify compliance with the
- amounts and composition of sludge disposed in the surface waters.
Monitoring of effluent quality may be also undertaken to:
- assess treatment performance;
- assess self-monitoring and reporting programme;
- meet regulatory/permit requirements;
- detect changes in effluent quality that could have an impact on the environment;
- provide data for long-term planning, and confirm the design criteria;
- meet research needs.
The nature and frequency of sampling required depend of on a large number of
factors, such as:
- sensitivity of the environment;
- regulatory requirements;
- nature of the treatment process;
- risk to the environment;
- quality of the environment;
- variability of the flow, daily and seasonal ;
- composition and variability of the inflow’s industrial waste component;
- reliability of the treatment process;
- competence of the operating staff;
- effectiveness of the plan’s maintenance and supervision;
- remoteness of the plant.
Because monitoring is a very expensive task it is necessary for it to be optimised. It is
recommended that sampling be made at two levels:
- a small number of critical parameters related to the treatment process and impact on the
- a broad suite of parameters covering all those with identified potential for impact on
Sampling should be more frequent in case of a larger treatment plant, in case where
there may be a significant impact on the environment, or in case of a sensitive environment.
Potential variability of the quality of effluent may influence sampling frequency. It depends on
the type of treatment processes. Processes with longer detention time, such are lagoons, are
far less likely to have sudden changes in effluent quality than the plants with short detention
Table 12 gives the recommended sampling frequency for different plants, which have
to be harmonised with relevant national regulations. Two sampling frequencies are
nominated for each plant size. In small, remote communities, as well as in regions lacking
adequate staff and equipment, sampling may be both logistically difficult and prohibitively
expensive. In these cases, processes used should be selected to be robust and reliable.
Then, sampling frequencies may be lower than indicated.
Composite sampling is more suitable for large plants and in cases when it is
necessary to estimate the total load and peak pollution load to the environment. Generally,
grab samples are more common. Sampling should occur within two hours of normal time of
the maximal daily flow for short detention time systems.
Other details related to monitoring could be found in relevant literature, as well as
standards and protocols.
Monitoring programme has to be properly designed in order to be efficient and
rational. Monitoring cycle (Box 6.) is a guiding principle: the process of monitoring and
assessment should be seen as a sequence of related activities that begin with the definition
of information needs and ends with the use of information product. Successive activities in
this chain should be specified and designed (optimised) on the basis of the required
information product as well as on the preceding part of the chain. A chain is only as strong as
its weakest link. Monitoring without the specification of information needs prior to the actual
network design will be a waste of money.
Box 6: Monitoring cycle
Elements of the monitoring cycle are:
1. Water management goals and needs
2. Information needs for the management
3. Monitoring strategy to gather information
4. Network design and optimisation
5. Sample collection
6. Laboratory analysis
7. Data handling
8. Data analysis, validation and approval
10. Information utilisation by management
Recommended sampling frequencies for effluents
Plant Type Principal Process Plant Detention Times Plant Size
(See notes below) Parameters Very Small Small Medium Large
< 0.5 MLD 0.5 - 3 MLD 3-20 MLD >20 MLD
A, B TSS, BOD-5 all Q Q W 2xW
C TSS long detention Q Q M W
BOD-5, COD, N short detention M W 2xW 2xW
D TSS, N, P long detention Q Q M W
BOD-5, COD short detention M W 2xW 2xW
E E. coli long detention Q Q M W
short detention M M 2xW 2xW
F any site specific needs all W W 2xW 2xW
Comprehensive suite of parameters all T T Q Q
NOTES: PLANT TYPE - TYPICAL TREATMENT PROCESSES
Treatment Process Category Parameters to be removed Examples of Treatment Processes
A Pre Treatment Gross solids, grit, grease and oil Screening
B Primary Treatment Gross solids plus readily settleable solid Primary sedimentation
C Secondary Treatment Most solids and BOD Biological treatment, physical-chemical treat., lagoons, natural treat.
D Nutrient removal Nutrients Biological treatment, chemical precipitation, natural treatment
E Disinfection Bacteria and viruses Lagooning, UV radiation, chlorination, natural treatment
F Advanced wastewater treatment Treatment to further reduce selected Granual-medium filration,microfiltration, membrane technology,
parameters membrane bioreactor
ABBREVIATIONS BOD = Biochemical Oxygen Demand, COD = Chemical Oxyen Demand, P = Phosphorus, MLD = Megalitres per day,
2xW = Twice weekly, M = Monthly, T = Twice yearly, Q = quarterly, N = Nitrogen, TSS = Total Suspended Solids, W = Weekly
Sampling frequency in very small remote communities may be lower than that indicated above.
Appendix 1: Glossary
Advanced wastewater treatment: the application of multiple unit processes beyond the
Beneficial uses: uses or value of the environment that promotes public benefit, welfare,
safety, health, and aesthetic enjoyment.
Catchment area: the area of land from which all surface runoff flows through a sequence of
streams, rivers and possibly, lakes to a particular point in a water course (normally a lake or a
Chlorination: the application of chlorine to water, wastewater, or industrial waste, generally for
Coastal waters: the waters outside the low water line or outer limit of an estuary;
Criterion: qualitative or quantitative value or concentration of a constituent, based on scientific
data, from which a decision or judgement may be made about suitability of water for a designed
Diffuse source discharges: a source of pollution that has no single place of origin (for
example, run-off of rainwater containing sediment, fertilisers and pesticides from land used for
Disinfection: a process that destroys, inactivates or removes pathogenic micro-organisms.
Domestic wastewater: wastewater from residential settlements and services, which originates
predominantly from the human metabolism and from household activities.
Effluent: the water discharged following a wastewater treatment process, e.g. secondary
Environmental flow: the flow in an inland stream needed to sustain the ecological values of
aquatic ecosystems at a low level of risk.
Environmental value: See beneficial uses, above.
Estuary: the transitional area at the mouth of a river between fresh-water and coastal waters;
Eutrophication: the process of an aquatic body becoming enriched with nutrients that stimulate
aquatic plant growth, such as algae, resulting in depletion of dissolved oxygen.
Floatables: Gross solids, plastic, foam or excessive oil and grease present on the surface of the
Guideline treatment level: a likely level of treatment for the particular set of discharge
conditions. Actual treatment requirements should be determined in accordance with
environmental value requirements and ongoing monitoring.
Groundwater: Subsurface water in a saturation zone or aquifer that can be extracted through a
Hazardous substances: substances or groups of substances that are toxic, persistent and liable
to bio-accumulate, and other substances or groups of substances which give rise to an
equivalent level of concern.
Lagoon: a shallow pond where sunlight, bacterial action, and oxygen work to purify wastewater.
Industrial wastewater: any waste water which is discharged from premises used for carrying on
any trade or industry, other than domestic waste water and run-off rain water;
Inland waters: all standing or flowing water on the surface of the land, and all groundwater on
the landward side of the baseline from which the breadth of territorial waters is measured.
Marine waters: oceans and bays together with water in estuaries. These waters have dissolved
inorganic ions greater than 30,000 mg/L.
Mixing zone: an area contiguous with an effluent discharge point and specified in the licence or
permit, in which the water quality objectives applying to the water body are not required to be
Municipal wastewater: see urban wastewater.
Municipal treatment plant: a plant treating wastewater of essentially domestic origins in which
any industrial wastes are compatible with domestic wastewater.
Natural treatment system: apply processes that take place in the natural physical, chemical and
biological processes. Most frequent applied: land-treatment systems - slow rate, rapid infiltration
and overland flow; constructed wetlands - free water surface, subsurface flow systems; floating
aquatic plants; aquaculture.
Nutrients: substances necessary for the growth and reproduction of organisms.
Nutrient removal: an additional wastewater treatment process to reduce the amount of
nitrogen or phosphorus in the effluent below the levels achieved by secondary treatment.
Objectives: the desirable, short and/or long term goals of the water quality management
program. Such objectives are often derived after consideration of water quality criteria in the
light of economic, environmental, social or political factors.
Organic material: in wastewater treatment, material that can be biologically consumed in the
secondary treatment process. A food source for various microorganisms.
Outfall: pie or conduit used to convey treated effluent to the point of discharge terminating in a
Point source discharges: a source of pollution from an identifiable place of origin (for example,
an effluent discharge from a wastewater treatment plant or an effluent discharge from a rural
Ponds: treatment lagoons for purification of raw wastewater and for the additional treatment of
primary or secondary treated effluent.
Pollutant: any substances liable to cause pollution.
Pollution: the direct or indirect introduction, as a result of human activity, of substances or heat
into the air, water or land which may be harmful to human health or the quality of aquatic
ecosystems or terrestrial ecosystems directly depending on aquatic ecosystems, which result in
damaged material property, or which impair or interfere with amenities and other legitimate uses
of the environment.
Priority substances: established priority hazardous substances.
Pre treatment/preliminary treatment: wastewater treatment, which involves the removal of gross
solids and some of the readily settleable solids, as well as removal of floating material, grease
Primary treatment: wastewater treatment, which removes readily settleable solids. It means
treatment of urban wastewater by physical and/or chemical processes involving settlements of
suspended solids or other processes followed by sludge digestion or other means of sludge
disposal. The BOD5 of the incoming water is reduced by at least 20% before discharge, and the
total suspended solids of the incoming wastewater are reduced by at least 50%.
Reuse: means the application of appropriate treated wastewater to some beneficial purposes.
River basin: the area of land from which all surface runoff flows through a sequence of streams,
rivers and possibly lakes into the sea through a single river mouth, estuary or delta.
Sanitation: control of physical factors in the human environment that could harm development,
health, or survival;
Secondary treatment: treatment of urban wastewater by processes generally involving biological
treatment with secondary settlement or other processes followed by sludge digestion or other
means of sludge disposal. The contaminants in incoming water are reduced to a minimum:
BOD5 70 - 90%, chemical oxygen demand 75 %, and total suspended solids 70 - 90 % before
Sewage: see wastewater.
Sewer: a channel or conduit that carries wastewater and storm-water runoff from the source to a
treatment plant or receiving stream. “Sanitary” sewers carry household, industrial and
commercial waste. Storm sewers carry runoff from rain. Combined sewers handle both.
Sludge: the residual solids, whether treated or untreated, which are removed from wastewater
Sludge treatment: processes in which the volume of water is reduced and sludge quality is
controlled in order to prevent detrimental environmental impacts.
Standards: currently legally enforceable levels established by an authority.
Tertiary treatment: processes, which further improve the secondary effluent quality prior to
discharge or reuse. Processes such as sand filtration, ion exchange, micro filtration, membrane
technology and the use of wetland filters are generally used.
Toxicant: a substance, which above a certain concentrations is poisonous to living things.
Trade effluent discharge standards: currently legally enforceable levels established by an
authority for the industrial wastewater prior discharge into urban wastewater system.
Urban wastewater: domestic wastewater or a mixture of domestic wastewater with industrial
wastewater and/or run-off rain water;
Wastewater: water which has been used, at least once, and has thereby been rendered
unsuitable for reuse for that purpose without treatment and which is collected and transported
through sewers. Wastewater normally includes water from both domestic and industrial sources.
Wastewater collection system: a system of conduits, which collects and conducts
Wastewater discharge: the flow of treated effluent from any wastewater treatment process.
Wastewater disposal: collection and removal of wastewater deriving from industrial and urban
settlements by means of a system of pipes and treatment plants.
Wastewater management: all of the institutional, financial, technical, legislative, participatory,
and managerial aspects related to the problem of wastewater.
Wastewater pollution: the impairment of the quality of some medium due to the introduction of
spent or used water from a community or industry.
Wastewater quality: the state or condition of spent or used water that contains dissolved or
suspended matter from a home, community farm or industry.
Wastewater reclamation: treatment and management of municipal, industrial, or agricultural
wastewater to produce water of suitable quality for additional beneficial uses.
Wastewater sanitation system: the combined collection, treatment and disposal system of
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